Northwest Nature Notes

SNOWY OWL FLIGHT YEAR

2012-01-05T10:07:00.000-08:00

The winter of 2011-2012 will go down in history as a time when arctic-breeding Snowy Owls (Bubo scandiacus) came down in great numbers to southern Canada and the northern United States. This happens at irregular intervals, and this time it has been six years since the last flight year in the Pacific Northwest.

These flights are called irruptions, a word meaning 'into an area' just as eruptions means 'out of an area.' The latter is used for volcanoes, the former for unusually large flights of birds or movements of other animals, usually detected where they arrive. In this case, our baseline is no more than a few birds observed each winter, whereas the irruptions involve dozens to hundreds of birds.

Snowy Owls have been reported from many localities since November, some of them birds that were seen for only a day or two, others birds that arrived and stayed put. Numbers inland are generally small, not much higher than in non-flight years, but the majority of birds are congregated near the coast.

Up to a dozen birds have been present on Damon Point, a spit on the north shore of the entrance to Grays Harbor, and these are the birds featured here. Even more are present along Boundary Bay in southern British Columbia. At both of these localities, numerous birds can be seen from the same spot, sometimes several perched together on a log. They seem not at all aggressive to one another. In addition, a few birds have taken up residence at Port Susan Bay and the Nisqually Flats.

There is still some confusion about exactly why the owls come down in numbers only at intervals. Earlier thoughts were that they did so after a lemming population crash, the absence of their primary food sending them south. But this has never been entirely satisfactory, because lemming population cycles in different regions are independent of one another, yet the irrupting owls appear over a very wide area.

An alternative gaining more credence is that during years of lemming population highs, the owls do very well, and so many young are produced that densities in the fall are higher than normal, and this sends many birds southward or perhaps in all directions. Thus our numbers are because of lemming booms, not lemming busts.

Lemmings are absent from this area, but voles are locally abundant, and some of the birds that make these flights may subsist on these lemming relatives.

In lieu of these rodents, many owls switch to a water-bird diet, which is why coastal areas are favored. Water birds usually roost right out in the open, either on shore or on the water, and if the owls go out at dusk to hunt them, their prey is at a great disadvantage. A white owl approaching in low light levels may be just about impossible to see against a paler sky. We still don't know if they continue to hunt through the night, but they clearly don't during the day, which is why we rarely see them doing anything but turning their heads and occasional preening.

Studies based on the collection of regurgitated pellets find these coastal owls eating shorebirds (Dunlins, Sanderlings, Red Phalaropes) and diving birds (Horned Grebes, Buffleheads) as well as Black Rats that live among jetty rocks. After the breeding season, some female owls fly out to the pack ice and presumably have nothing to eat but water birds.

One last thought. These owls are magnificent additions to the local scene whenever they favor us by their presence. Although they seem tame and placid, it's always best to avoid getting too close. Each owl has its own flight distance, and observers and photographers should be sensitive to that.

Dennis Paulson

UNDERWATER DRAMA

2011-12-29T16:29:00.000-08:00

One night late in December, a small group of us decided to check out Puget Sound at Seahurst during a minus 1.5 foot low tide. At extreme low tides, you can find all sorts of marine invertebrates close up and personal. Unfortunately, low tides occur at night during the winter, so you have to go out with a strong flashlight and, most of the time, bundled up in parka and rain gear to have this experience. We were lucky: moderate temperature, no wind, no rain at 10 pm. The water was calm and clear as a windowpane, and the exposed beach was covered with critters.

It takes a while to get the hang of it. You have to distinguish stationary animals, many of them sessile filter-feeders, from multi-hued rocks and gravel and sand. Many of them are exposed by the receding tide, while others shelter in crevices, among algal fronds, or under rocks. On this visit, we looked mostly on the surface, as there were very few rocks of the right size to turn. But by doing this, you can find many more critters, including several species of fishes. But always replace the rocks carefully!

Mollusks of numerous kinds, including limpets, lined chitons (Tonicella lineata) and rock oysters (Pododesmus cepio), were scattered over the large boulders that were exposed by the low tide. There were scattered plumose anemones (Metridium senile) hanging down obscenely from rocks and Christmas anemones (Urticina crassicornis) looking like prettily patterned blobs. We found one attached to a movable rock, so we took it out in a foot of water to let it expand. We came back to it 10 minutes later, and it was nicely expanded for photos.

As we were photographing it, a kelp crab (Pugettia producta) approached from stage right. It came up to the anemone and started feeling in its tentacles. We wondered if it might be snipping them off to eat, but we couldn't be sure. More likely it was feeling for organic matter left among the tentacles, perhaps part of the anemone's last meal. Several times after inserting a cheliped among the tentacles, it brought it back to its mouth. After a short while of doing this, it started running one of its longer legs through the tentacles, almost in a grooming manner. Perhaps the leg was able to detect food particles?

Presumably the thick chitin of the crab's legs protected it from the anemone's stinging cnidocytes, and a coating of anemone mucus might have conferred additional protection.

As we were watching this, a red rock crab (Cancer productus) approached the kelp crab, and it scuttled away about a meter and sat among the eelgrass. The second crab didn't interact with the anemone but then found a dead Dungeness crab (Cancer magister), perhaps to check it out as dinner, but our lights may have scared it away. We had earlier found a pair of Dungeness crabs mating in an eelgrass bed.

Sea stars were the most conspicuous megafauna appearing in our lights, including sunflower stars (Pycnopodia helianthoides), many of them young, and ochre sea stars (Pisaster ochraceus), with fewer mottled sea stars (Evasterias troschelii). We turned one Pycnopodia over that had a hump in the middle and found what I thought was a fish skull clutched in its hot little tube feet. We grabbed the skull and started pulling on it and out from what must be an amazingly large stomach came a spotted ratfish (Hydrolagus colliei) carcass, largely digested!

On a previous occasion at the same site, we had found a Pycnopodia that had ingested a whole rat. We assumed the rat had been dead in the water rather than that the starfish had gone on walkabout up in the rocks. This huge sea star really seems at the top of the intertidal Puget Sound food chain!

Dennis Paulson

SALMON AND EAGLES

2011-12-13T09:49:00.000-08:00

One of the more spectacular natural phenomena of the Pacific Northwest is the annual spawning of five species of Pacific salmon (Oncorhynchus).

The Harrison River is one of the major tributaries of the Fraser River in southwestern British Columbia. Every fall my wife and I make a pilgrimage to the Harrison to see this phenomenon. The salmon are spectacular to watch, although we see very little actual spawning, just the great number of fish, both alive and dead. The dead ones have presumably spawned, as Pacific salmon spawn only once in their life and then die.

The attribute of breeding only once is called semelparity, and it is more typical of organisms that live only one year, usually called "annuals." There are many annual plants among our wild flowers and quite a few annual animals as well, mostly small ones. Hatch or sprout, grow rapidly, breed. and die are the usual course of events for an annual animal or plant.

Pacific salmon, on the other hand, have a fairly complex life cycle. They hatch in fresh water, where they may spend up to a few years, then move into the marine environment, where over an additional few years those that survive grow large and strong, prepared to come back to the river system and the very stream where they were hatched. They swim upriver some distance, spawn, and then die. That's what all those salmon are doing in the Harrison River.

Some of them are there because of human activities. Hatcheries on tributaries of the Harrison raise the young fish in tanks, where they are protected from predators, then release them when they are ready to travel downstream. When they come back as breeding adults, they are captured and bred artificially by applying sperm extracted from the males to eggs extracted from the females, and the cycle begins again.

The Harrison River system has many thousands of fish of four salmon species—chinook (O. tshawytscha), coho (O. kisutch), chum (O. keta) and sockeye (O. nerka). You'll notice the scientific names from Russian; all of our species occur as well on the other side of the Pacific Ocean.

When very large runs are in the river system, especially from October to December, the dead and dying fish support great populations of predators and scavengers. Among them are gulls, crows, ravens, and—most notably—Bald Eagles.

Eagles come to the Harrison in the late fall by the thousands. I have estimated as many as 500 visible from one spot, although that was a rare sighting. More likely, a visitor who stops at several places along the river may see a few hundred birds, sometimes a dozen roosting in the same tree or a hundred spread out over the river flat.

Interactions among the birds are commonplace and make the experience a memorable one. The whistled calls of the eagles, the flowing river, the conifer background, and, if you're lucky, the blue sky, all make the experience a memorable one. The smell of rotting salmon carcasses adds an extra dimension not available on all nature trips.

Dennis Paulson

RAPTORS IN THE CITY

2011-11-30T09:11:00.000-08:00

One of the surprises in studies of urban wildlife in recent years is the invasion of our cities and suburbs by predatory birds such as hawks and owls. Perhaps "invasion" is too active a word, and a better word is "acceptance." More and more raptors are apparently becoming comfortable with living in the cities of the Pacific Northwest and, in fact, all across North America.

Bird feeders have become a dependable part of the urban/suburban environment, and many small birds are attracted to them. The juncos and finches and sparrows that abound at feeders attract Sharp-shinned Hawks in winter, but the hawks leave for the mountains in spring. However, their larger relatives Cooper's Hawks are year-round residents, feeding on pigeons, jays, and flickers and nesting in wooded areas that give them a sense of security. The males are conspicuous in spring, with display flights and vocalizations, so more and more of them are being detected living among us.

Merlins too are in the process of becoming city dwellers. These small falcons nest in forests near open country, where they usually capture their prey (small birds). Wintering Merlins probably moved into cities to take advantage of local concentrations of small birds, and eventually pairs remained throughout the year and nested because of that prey abundance. Their nesting efforts have been successful, and the population of urban-nesting Merlins has slowly risen.

Barred Owls have moved into the Pacific Northwest from the north, and they too appear to be comfortable in wooded parts of our cities. Preferred prey include the gray squirrels and rats that have been introduced into the region, and our bird feeders attract and concentrate these mammals as well. There are now pairs of Barred Owls, Cooper's Hawks, and Merlins nesting in wooded areas near my house in Seattle that weren't there 10 years ago.

Red-tailed Hawks do not live around dense housing developments, but large parks and open spaces furnish adequate hunting grounds for rats and squirrels, and if any trees in their territory are large enough to support their nests, they may nest in our cities. Many more of them appear in winter to hunt in open areas around parks and airports.

The Great Horned Owl is a top predator surprisingly willing to live in cities, mostly in relatively large parks. It is large enough and fierce enough to handle mid-sized mammals such as raccoons, opossums, and domestic cats that thrive in cities. Crows and pigeons furnish abundant prey populations as well. Nest sites (usually old Red-tailed Hawk nests) may be limiting, however.

Even more surprisingly, after a long period of decline during the DDT era, Bald Eagle populations have rebounded in the Northwest, and they not only visit but even nest in the cities, often in large parks near water where prey species such as waterfowl and fish are available. They need large trees for their huge stick nests.

Whenever a shift like this occurs, it is worth trying to distinguish between behavioral adaptation and genetic adaptation. Have these birds "learned" that cities are OK? Or are there genes for city living that have become favored? Are there genes for increased tameness, recognition of bird feeders as sources of bird concentrations, resistance to being mobbed by crows? Actually, cities aren't bad places to live for mobile predators such as these, as there may be local sources of abundant food and some of their own potential predators may be absent. Also, the first individuals to accept life in the cities have no competition from others of their species!

Dennis Paulson

BLACK-TAILED GULL IN COMMENCEMENT BAY

2011-11-14T14:46:00.000-08:00

In the fall of 2009, a Black-tailed Gull (Larus crassirostris) showed up roosting on a log boom on the east side of Commencement Bay, near Tacoma. It was found on October 13 by Charlie Wright and remained for about a month, seen almost daily until November 7. I remember that date well, as it was seen that morning. That afternoon, Netta Smith and I were finally able to accompany Shep Thorp in his boat, the best way to see the gull, but we were unable to find it. It had presumably headed south with the large numbers of California Gulls that had been present until that time.

In the fall of 2011, presumably the same bird showed up at the same spot. First seen by Shep on September 14, it was still present as of November 4 but may have departed soon after that. During both of its visits, this bird was seen by many enthusiastic observers, mostly at a distance of several hundred yards, spotting-scope range. By far the best way to see it was to go out in a small boat and circle the big log boom on which it roosted daily with hundreds of other gulls.

On November 4, Netta and I brought our kayak down from Seattle and launched it from the Gilmur access point on the bay. Very quickly we found the Black-tailed Gull and captured a few mediocre photos. Then something spooked them, and a bunch of the gulls took off. We saw our bird head across the bay and disappear in the distance, very disappointing. But we weren't discouraged, as the day, although threatening rain, had turned beautiful, with the low afternoon sun illuminating the maple-covered hillside in front of us.

We maneuvered the kayak around the log boom and found a place to enter it, giving us better light for photography. The boom was covered with gulls over much of its length, with photo ops abounding. Double-crested Cormorants roosting on it didn't like us at all, and they took off when we were a hundred yards away. Harbor Seals watched us but stayed put until, in a few cases, we got too close for their comfort level. The gulls just mostly sat and watched us paddle or drift past as close as 30 feet from them. They are surely used to curious kayakers by this time.

The most abundant gulls on the boom were Bonaparte's and Mew, at least several hundred of each. Among them were dozens of California and a few Thayer's and Glaucous-winged. We scrutinized the flock carefully and were able to find no other species. While slowly moving around the boom, we found to our delight that the Black-tailed had returned. We were able to get photo after photo of it as it watched us; it often rested with eyes closed, comfortably napping. When we got a little too close several times, it hopped onto another log, giving us the opportunity to photograph it with a different species.

Among the hundreds of gulls, the lack of immatures was noteworthy. There were no immature Bonaparte's and only a few immature Mew and California, a far lower proportion than would have been in their populations. Obviously immature gulls were not using Commencement Bay, or perhaps they weren't roosting. Do they have a harder time finding enough food and therefore have to continue foraging for a longer time? That makes sense, and the timing of mature vs. immature gulls at roost sites would be an interesting research project.

Another point of interest was the variation in leg color in the adult gulls. We noted such variation in Bonaparte's, Mew, California, and Thayer's, usually from duller to brighter. Bonaparte's varied from pale pink to red-orange, California from yellow-green to blue-gray. Thayer's are supposed to have rather bright red-pink legs, but one adult had very pale whitish-pink legs.

In any case, my luck had changed; it turned out that this was probably the last time the gull was seen!

Dennis Paulson

ODONATE OVIPOSITION

2011-11-03T10:05:00.000-07:00

Egg laying is a very important part of the life of an insect, as the number and placement of the eggs influences where the larvae that hatch from them will live and how many of its own species it will have to compete with. The presence of other animals that are potential predators on the eggs must also be taken into consideration. Oviposition occurs in two quite different fashions in the dragonflies and damselflies, order Odonata.

Exophytic egg-layers extrude fertilized eggs, often in a clump, through the genital opening in their eighth abdominal segment. The female flies over the water, stopping at intervals to descend to the surface and tap the abdomen in the water, releasing the cluster of eggs. This mode is characteristic of most dragonfly families, for example skimmers (Libellulidae), emeralds (Corduliidae), and clubtails (Gomphidae).

There are several variations on this theme. Numerous species splash eggs onto the adjacent bank in drops of water, perhaps to make the eggs safer from aquatic predators. The larva will find its way to the water upon hatching. Some members of the skimmer family drop single eggs one at a time onto dry land in basins that fill up with winter rains. Their larvae develop during the spring and emerge as adults in midsummer, then hanging around as the pond dries up to lay eggs in the pond basin after it dries up in the heat of late summer.

Others actually deposit their egg masses on leaves and stems above the water, and the larvae drop into the water when the eggs hatch.

Dragonflies of the darner family (Aeshnidae) and all damselflies are endoophytic egg layers, utilizing a quite different oviposition strategy. These odonates have well-developed ovipositors at the end of the abdomen, and they insert eggs singly or in pairs into plant tissues. These eggs are much better protected against predation than the exophytically laid eggs, placed precisely rather than scattered, and fewer of them are laid.

Endophytic ovipositors typically have a clutch size (the number of eggs matured in one batch) of one to two hundred eggs and typically lay only a few clutches. However, long-lived females may lay more clutches, eventually totaling in the low thousands of eggs in their lifetime. Exophytic ovipositors lay smaller eggs more quickly (up to 300/minute in some species), and their clutch sizes are larger, in the thousands, but with lifetime totals perhaps no higher than the longer-lived endophytic species.

Oviposition sites are presumably chosen as good larval habitats, and several egg-laying females will often collect at the same spot, presumably attracted by the ones already there.

Because female dragonflies are a scarce resource at the water, males will always try to mate with them, and in many species, the male stays hooked up to the female with which he has mated through the oviposition process to keep other males away from her. Thus both exophytic and endophytic ovipositors may be seen doing so in tandem.

Dennis Paulson

A HALLOWEEN TREAT

2011-10-28T17:29:00.000-07:00

A spooky Halloween story or chilling thriller film is incomplete without the appropriate array of creepy nighttime animal sounds. Unfortunately, many an evening stroll has been transformed into a terrifying, heart-pounding experience thanks to these bloodcurdling calls. In fact, we can encounter a variety of these sounds right here in the Pacific Northwest! And because we only fear what we don't understand, here is a brief guide to the spookiest of our local animal sounds to help you learn more about these relatively harmless creatures.

Barred Owl - Strix varia L: 21"
Common, year-round resident of the Puget Sound region. Often found in mixed coniferous-deciduous forests and seen during daytime hours near roosts. Calls include very loud hooting/barking, often described as monkey-like sounds. Individuals may also hiss or cackle.

Listen

Boreal Owl - Aegolius funereus L: 10"
Uncommonly seen inhabitant of montane forests in Eastern Washington. Found in mixed coniferous-deciduous northern forests. Call is a series of low, piping hoots that rise and fall in pitch and intensity. Also gives a low, nasal hooAh as well as short screeches.

Listen

Great Horned Owl - Bubo virginianus L: 22"
Fairly common and widespread, inhabiting a variety of habitats including forests, deserts, tundra, and urban areas. Often seen perched at dusk or mobbed by small birds in the daytime. Call is an iconic series of rhythmic hoots associated with most midwinter forest settings.

Listen

Western Screech-owl - Megascops kennicottii L: 8.5"
Common in wooded to sparsely wooded areas including urban parks, native woodland, and deserts. Generally roosts in very dense, dark areas and is difficult to see in the daytime. Call is a series of accelerating, abrupt whistled hoots that ends slightly lower in pitch.

Listen
(Can you hear the coyote in the background?)

Barn Owl - Tyto alba L: 16"
Extremely widespread species common to Western Washington. Prefers open grassland habitat and roosts in cavities or human-made structures. Populations may be in decline. These birds do not "hoot" like other owls. Calls generally only a shrieking screech. Very commonly thought to be a frightening, ghostly critter, but its silent flight and phenomenal hearing make it one of nature's best mouse-exterminators.

Listen

Northern Pygmy-owl - Glaucidium gnoma L: 6.75"
Widespread in coniferous forests throughout Washington. Some may migrate to lower elevations in winter months. Call is a regular, repeating series of tooting hoots. Listen for these distinctive calls at dawn and dusk.

Listen

Coyote - Canis latrans L: 45" H: 24"

Common throughout a variety of habitats, especially open areas and clearings. They have adapted well to the presence of humans and have expanded their ranges since the disappearance of the Gray Wolf. Sounds include yips, yaps, whines, barks and bone-chilling howls.

Listen (yips, yaps, barks, howls)
Listen ("moonlight howl")

Red Fox - Vulpes vulpes L: 40" H: 15"
Prefers brushy open habitats throughout Washington, but generally avoids densely forested areas and higher elevations. Varies in color from black to gray-brown. Sounds include barks, whines, wails and a fairly frightening scream (see video below).

Listen

-Robert Niese
Education and Outreach Coordinator

WOULD YOU BELIEVE A MILLION MEADOWHAWKS?

2011-10-14T14:14:00.000-07:00

Yes, I said a million. Or perhaps 10 million or 100 million. Netta Smith and I visited Harney County in south-central Oregon on 24-26 September 2011 to look for birds, which as usual were in great numbers. But we were struck even more by the numbers of odonates. Rather than diversity, we found abundance. Two species were there in prodigious numbers like I have never seen before.

Striped Meadowhawks (Sympetrum pallipes) were the most abundant and ubiquitous. Our first stop near water was at a big pond on the east side of Hines. As soon as we stopped, we saw there were Sympetrum everywhere. On our first afternoon, the temperature reached 92° F, what I would call very hot. We stopped several times along highway 205 south of Burns and saw that the barbed-wire fences were covered with meadowhawks. They clearly chose to perch on the barbs rather than the wire between them, and in some places there was a dragonfly on just about every barb.

We stopped at Wrights Point, a long rocky ridge that extends out into the Blitzen River basin, and were flabbergasted at the numbers of Striped Meadowhawks there, flushing from the road and shrubs and dead tree branches. In addition, there were hundreds of Spotted Spreadwings (Lestes congener) in the shrubbery, only visible at closer range, although occasionally one would just fly across in front of me, perhaps flushed by one of the meadowhawks we were scaring up.

We got back into Burns at about 6:30 pm, and I immediately noticed dragonflies going past, a real flight. In all directions there were meadowhawks heading just a little east of south, right into the face of a moderate breeze. We estimated at least 10/minute passing in front of us, and we walked 50 yards to the grass behind the station and saw the same numbers. If they were flying over a broad front, there were hundreds/minute.

The sky was clouding up, and the flight fell off after about 15 minutes. At 6:45, there were still a few dragonflies passing, and there were many perched in the bushes. The flight seemed exactly like a migratory flight, yet the species is not known to be migratory, and I presume this was a local flight, perhaps individuals dispersing to find new breeding areas. I wondered if the high density of individuals would lead to such a flight.

The second day dawned cool, cloudy, and windy, and odonate activity fell dramatically. Nevertheless, the high temperature reached about 60° F., and we still saw meadowhawks and spreadwings wherever we stopped. It was warm enough that they were well able to fly as we flushed them, and many of them were perched in the same situations as on the preceding and following sunny day. The third day dawned clear and cold, but it warmed up rapidly to a high in the low 70s before we left the area to head back to Seattle.

On all three days, we stopped at additional oases of trees and shrubs in the midst of the vast prairie, shrub-steppe and wetland habitats, and every one of them was full of both Sympetrum and Lestes. As we walked along dirt paths, the meadowhawks rose one after another and fluttered off. We could look up a path and see them all over the sunlit ground. A diversion into the edge of any patch of woodland would reveal spreadwings all over the branches and twigs.

In several areas both species were perched on rock walls and sidewalks, the Lestes alongside the Sympetrum. As we flushed them, many of them ended up landing again near another, which in turn would flush, a chain reaction of fluttering. All the odonates were sexually mature; I never saw one that I could call immature.

Perhaps the third day was the most surprising. As we drove along a road through open fields just east of Burns at 11:30 am, temperature around 70° F, we started seeing Sympetrum flying across the road as we had on the evening of the first day. But they were in copulating pairs, not individuals! They were moving in the same direction as before, just east of south but still into a light breeze. I speculated that the wind direction was setting the flight direction, but who knows? This flight lasted the half hour that we were in that area and extended across at least a mile of road. Clearly thousands of individuals were participating.

As we drove into Burns at about noon, the flight was still going, patchy because of large buildings and areas of dense trees, but whenever we were in the open, there they were, crossing busy highways, all in exactly the same direction. Perhaps 10% of the individuals were single, but all the rest were in the wheel position. It was a fantastic sight. We saw no evidence of oviposition anywhere, nor did we see any sign of breeding in the spreadwings, yet I have no doubt that it took place somewhere.

We had to leave and started west on highway 20 toward Bend. There were still pairs going across the road up to about 10 miles west of Burns, then we saw no more but a few singles. We stopped in a rest area 16 miles west of Burns, and there were Striped Meadowhawks and Spotted Spreadwings all over the open grass, perched on the ground and in shrubs. Still the same species in abundance, but there was no mating, no flight. We stopped again at Hampton Station, much farther west, and again saw a few meadowhawks, but nothing in the air.

These observations were of the greatest interest to me in several ways. (1) I have never seen so many individuals of an odonate species spread over so much landscape. Underestimating all the time, I decided there was a minimum of 100 individuals/acre, and I think it was more like 1000/acre in many places. I thought the dragonflies were distributed over an area at least 50 x 30 miles, or 150 square miles. 150 square miles = 96,000 acres. At 100/acre, there were 9.6 million meadowhawks. Or perhaps there were 10x that many.

(2) Where did they all come from? Both species oviposit over dry land, then the basin fills with water during the winter rains, and the eggs hatch that spring, the larvae develop over the summer, and the adults are present in fall. So these individuals came from whatever wetlands filled during the winter of 2010-2011 and contained their eggs. 2011 has been an especially wet year, on the other hand, with Malheur Lake filling a huge area, so the eggs that were there produced a lot of larvae, thus the numbers of adults we saw.

But just a year ago, in spring 2010, there was almost no water in Malheur Lake, and the whole basin was dry, dry, dry. That would have provided much habitat for widespread oviposition of meadowhawks and spreadwings. But if it was dry, where did those adults come from? The puzzling aspect of this is that eggs had to be there in the first place from some previous successful year, and 2010 should have been a poor one for these species, with little water and thus few eggs hatching and relatively few adults. Is it possible that the eggs of these species (and of course other odonates) can lie dormant for multiple years?

(3) The meadowhawks were active in the sun at shockingly low temperatures on the third day. I saw several in flight when our car thermometer (known to be accurate within a degree or two) read 39° and 42° F at two stops. I have no idea how much their body temperature could have been raised by basking, but I almost never see odonates when it is colder than 55° F.

(4) We were really surprised to see no other species at all, except for the very occasional Blue-eyed Darner (Rhionaeschna multicolor); about a half dozen were seen over the three days, usually foraging in the lee of a tree grove. We checked several ponds and found nothing at all flying at them. How could one see a million odonates and see only three species?

As is so often the case in nature, observations generate more questions than answers.

Dennis Paulson

MIGRATORY MONARCHS

2011-10-03T14:18:00.000-07:00

The Monarch (Danaus plexippus) is surely the best known of North American butterflies. Occurring all across the continent, as well as on several other continents, this big orange butterfly with a vivid black-lined pattern delights all who see it. Like the swallowtails, it is the epitome of butterflyhood, bouncing across meadows and sipping nectar from a wide variety of flowers.

At this time of year, Monarchs all across North America head south for the winter. The vast majority acome from the eastern two-thirds of the continent. They fly south in trickles, then streams, then rivers converging on just a few areas in the mountains of central Mexico, wintering grounds not discovered by scientists until 1975. Many fewer (about 5% of the total population) head for the Pacific coast to winter in a few coastal groves in California.

Although many insects are migratory, this one is the most noteworthy in the US because of its large size, bright coloration, and great numbers of individuals on the move at once.

If you live near milkweed plants (Asclepias species), you may be very familiar with Monarchs. The beautiful flowers of milkweeds give no hint of their toxic nature. The plants have a milky sap full of cardiac glycosides, chemicals that affect the sodium-potassium pump in vertebrate cell membranes and can cause tachycardia and ventricular fibrillation, both very stressful to the human heart. The sap is also viscous and bitter tasting and caustic to our mucous membranes.

Monarchs breed on milkweeds, and their caterpillars are among the small number of insects that have evolved a resistance to the harmful effects of milkweed sap. They munch it with no worries throughout their development. The sap confers unpalatability and distastefulness on the larvae, and their bright aposematic coloration serves as a warning flag to potential predators.

The poisonous qualities of the milkweed are carried through metamorphosis, and the butterflies are also distasteful, unpalatable, and probably warningly colored. They are left alone by vertebrate predators, although invertebrates such as dragonflies can handle them.

Monarchs are large and conspicuous, not especially fast flying, and if they weren't distasteful they would probably be the object of much predation during their migrations and certainly on their communal roosts. In fact, they probably roost communally to concentrate the warning to predators that they are not to be touched.

Monarchs are nowhere nearly as common in the West as in the East, and in Washington state they are downright uncommon. It's always thrilling to see an adult or larval Monarch in the Columbia Basin, where they are associated with the big milkweed Asclepias speciosa. Presumably our Monarchs head south to the California roosts.

After overwintering, Monarchs take off for the North. They move back into southern US and breed where they stop. Their larvae develop quickly in the spring and, as soon as they are out of the pupa, the adults head north like the previous generation. They are one-way migrants, and they will stop somewhere in the northern US or even southern Canada to breed. There may be as many as three northbound migrant generations, before their offspring head off in the other direction, back to the wintering ground.

Dennis Paulson

TIGERS OF THE SAND

2011-09-20T12:23:00.000-07:00

Go to a sandy beach or an open patch of sandy soil just about anywhere in the summer and you are likely to see tiger beetles. You will at first see these diurnal insects running ahead of you. Their long, slender legs propel them over the ground at amazing speeds. If you get too close, they jump into the air, open their elytra (wing covers), and quickly fly away. They usually land nearby, and you may be able to follow individual beetles until one lets you get close enough for prolonged observation.

But look quickly, as they are likely to run and stop, run and stop as they hunt for prey. They have exceptionally long, sharply pointed, tooth-lined mandibles, with which they capture other insects and spiders. They make short work of their prey and move on to hunt again. Their vision is superb, both to find prey and avoid predators.

Even though they are alert and fast, they do have predators, including birds, lizards, and robber flies. Birds such as kestrels and flycatchers capture them in the air, shrikes on the ground. As well as their obvious adaptations, some tiger beetles secrete defensive chemicals that presumably protect them from some predators.

The cuticle of tiger beetles is somewhat iridescent, and although the majority of species are sort of a bronzy brown, many of them are brightly colored, usually green but sometimes purple or blue. Some species are polymorphic, coming in two or more of these colors. The undersides are often more metallic than the upper surfaces. Some species have red abdomens that show up when they fly. Most tiger beetles have a characteristic pattern of spots and lines on their elytra, and variations on that pattern are often what define different species.

Unlike many insects, when tiger beetles mate they both face the same way, so they can continue to run across the ground (but not to fly) when the male is perched on the female's back. This lessens the likelihood of predation when they are in this vulnerable state. A male may remain on the female's back after copulation to keep other males from mating with her. Females lay their eggs, one at a time, into the soil in places appropriate for the larva.

Tiger beetle larvae are just as predacious as the adults, but we don't see them at work. They live in burrows in the sand, covered except for a hard head capsule and a pair of mandibles. When another insect comes too close, they reach up from the surface and grab it, then pull it down into their burrow, to which they are anchored by hooks on top of the fifth abdominal segment. They have been known to capture dragonflies of much larger size that had the bad luck to land right at the mouth of a burrow.

There are 17 species of tiger beetles known from Washington state, all in the day-active, brightly colored genus Cicindela except for two nocturnal black species of Omus. Few of the species are statewide; most have limited ranges on one side of the Cascades, up in the mountains, or along the coast or big rivers.

Fortunately for aficionados of this group, there are two fine books available:

A Field Guide to the Tiger Beetles of the United States and Canada, by David L. Pearson, C. Barry Knisley, and Charles J. Kazilek, Oxford University Press, 2006.

Tiger Beetles: The Evolution, Ecology, and Diversity of the Cicindelids, by David L. Pearson and Alfried P. Vogler, Cornell University Press, 2001.

Dennis Paulson

A LOT OF DRAGONFLIES

2011-08-03T16:28:00.000-07:00

The Spiny Baskettail (Epitheca spinigera) is a dragonfly of the emerald family (Corduliidae) that occurs all the way across North America from Atlantic to Pacific. It is common in southern Canada and the northern tier of US states. It breeds in lakes, and apparently it can become very common in its optimal habitats.

It shares with numerous other species of Odonata the life-history trait of overwintering in the final larval instar and thus being ready to emerge as soon as its aquatic habitat warms sufficiently in spring. When this happens, apparently most of the larvae in the lake are ready to emerge at about the same time, so there are massive emergences over a period of a few days. I have yet to witness one of these (the larvae actually crawling out of the water, splitting their skins, and the adult that emerges flying away), but I did see the aftermath.

These scenes greeted us one sunny morning in June in southwestern Manitoba. Spiny Baskettails, hundreds and hundreds of them of both sexes, were hanging from every bare twig for several hundred meters along the entry road to Lake Audy in Riding Mountain National Park. The location is outside the Northwest, but the species occurs in the Northwest, so I consider it fair game.

Several things were of interest, besides the sheer staggering numbers of them. Very few were flying around, yet I would have thought there would be many prey insects in the air on this nice warm morning. Secondly, not a single one was resting on a leaf; every individual was hanging from a bare twig, even though it meant that when one was dislodged, it wasn’t that easy to find a new perching spot.

Several times we saw one try to land on the abdomen of a perched individual, but they were always shaken or buzzed off. All individuals were obviously immature, with reddish eyes. During sexual maturation, the eyes become glowing blue-green.

The sexes can readily be distinguished with a good view. Males have a slightly more slender abdomen base, with secondary genitalia projecting downward near the base, and three terminal appendages (two dorsal and one ventral). Females lack the bump at the base and have only the two dorsal appendages at the tip.

Mother Nature was showing off her profligacy in a big way here in an aspen woodland at the southern edge of the Canadian boreal forest.

Dennis Paulson

FOXES IN PARADISE

2011-07-05T09:11:00.000-07:00

My wife Netta Smith had an interesting story and photos for me. She spent a day in late June snowshoeing at Paradise, in Mount Rainier National park, and had an encounter with a family of Red Foxes (Vulpes vulpes) there.

Near the lodge, she saw a young fox lying on the roadside in a very relaxed manner and realized its den was right there, below the road. An adult fox watched from a nearby snow bank. As she watched, the cub got up and went over to check out a nearby marmot carcass, presumably brought as food. She moved on and left them to relax, but the next morning she returned to see additional activity.

An adult fox, probably the same one, was coming down the road toward her and seemed to be carrying something large. As it approached closer and closer, she realized it was a stuff sack, perhaps pilfered from some careless visitor. The nearest concentration of visitors was about a half mile away.

The fox deposited the stuff sack on the roadside just above the den, and Netta decided to check the sack for contents. She dumped it out and found a variety of food items, all neatly wrapped. She took the wrappers off the energy bars and gels to get rid of the litter that would surely have been produced by the fox. She took the beef stroganoff, which she knew made a delectable meal, as a reward for being a good citizen.

She threw each of the food items out on the snow about 20 feet away, and the fox didn’t hesitate to go over and pick up each one, take it a little farther away, and bury it in the snow. She photographed it carrying one of the items.

Meanwhile, another cute fuzzy foxlet came up out of the den to see what was going on, and the adult and young trotted off together. The young ran around on the snow in what could only be described as frolicking.

We have seen foxes at the Paradise parking lot on previous visits in the winter, and apparently there is a resident family, some of which are ridiculously tame. They run out into the parking lot and make the rounds of not only the cars but also the people using the parking lot as a picnic site. People surely are feeding them, notwithstanding the park signs to the contrary, with predictable results.

Red Foxes are native to the Washington Cascades, and they are all beautifully colored in black, gray, silver, and light reddish, with black legs and white tail tip. Red Foxes are also introduced into the lowlands of the Pacific Northwest, and those foxes are a much more typical bright reddish color.

Dennis Paulson

NAKED IN THE OCEAN

2011-06-23T17:00:00.000-07:00

It’s time to home in on the extreme low tides we get in our local marine environment during daylight hours in the summer. Get to the coast an hour before the low and spend a couple of hours looking in the shallow water and especially in pools left by the receding tide. If the pool is rich enough, just sit down and enjoy watching the invertebrates and fish, if there are any, go about their business.

But don't think you have to shed your clothes; the nudity here involves the animals you are watching. Among the animals that inhabit such places are the nudibranchs (= naked gills). These are mollusks that appear to lack shells, something like seagoing slugs; many have prominent external gills. Like slugs, they are members of the class Gastropoda, which includes the snails. Having dispensed with a shell gives the nudibranchs both constraints and opportunities.

The primary constraint, of course, would seem to be a much greater risk of predation without a hard shell into which to retire when disturbed. Along with this is the risk of desiccation when exposed at low tides, so you won’t find many nudibranchs sitting around on exposed rocks like you do some of the snails.

These are mostly small animals, ranging from 1 cm (Rostanga) up to 20 cm (Peltodoris), but because of their conspicuousness and beauty, they are more admired and sought by tidepoolers than some of the other invertebrates that share their habitat.

Prominent anatomical features are two tentacle-like structures toward the front that are called rhizophores and are probably chemical detectors. Toward the rear there may be a ring of gills. And projections all along the upper surface are cerata, the bright colors of which are probably involved in predator deterrence, a warning coloration that goes along with distastefulness.

The lack of a shell has provided selective pressure for nudibranchs to develop other ways of protecting themselves from predators, and one of the most effective is the ability to secrete chemicals, including sulfuric acid in some cases, that make them inedible. They are surprisingly predator-free, and fish have been seen to spit them out. Anything as conspicuous as some of these are would seem to be predator resistant!

One of the opportunities for such animals comes in the form of being free to be predators themselves. They often specialize in animals that aren’t eaten by many other predators, thus assuring them a reliable food supply. Most of their prey items are sessile, fixed to the rocks on which they crawl, but a few are able to capture motile animals as well.

Acanthodoris eats colonial ascidians (tunicates) and bryozoans. Triopha and Janolus eat arborescent (branched) bryozoans. Doris and Peltodoris eat sponges, especially the crumb-of-bread sponge (Halichondra), and how they avoid being pierced by the sponge spicules hasn’t been determined. These two species are called sea lemons. The tiny Rostanga eats red sponges, on which it may be perfectly camouflaged. Hermissenda eats hydroids and incorporates their toxic nematocysts into its cerata, thus affording it protection from predators. Dirona eats everything, including not only the same prey as the others but also snails and crustaceans.

The species shown here were found at two localities on the north coast of Oregon in May. All are common in Pacific Northwest waters.

Dennis Paulson

THE CHORUS OF THE CHORUS FROGS

2011-06-02T17:21:00.000-07:00

Early every year in the Pacific Northwest a familiar sound rings out, telling us it is spring whether it seems that way or not. this is the “song” or advertisement call of the male Pacific Chorus Frog, Pseudacris regilla.

Most people recognize the call immediately as the generic frog call of movies in decades past. As this is a common frog (or at least used to be) in Hollywood, California, its call was incorporated into many a movie that needed frog calls as ambience. In fact the “ribbit, ribbit” sound has become the stereotype of frog calls.

These frogs come out of their winter dormancy very early in spring, when, to paraphrase Robert Burns, a young frog’s fancy lightly turns to thoughts of love. The only way a frog has to express itself in such a situation is to call . . . . and call . . . . and call. And that they do, with surprising strength.

When a male frog feels these stirrings, he heads for the nearest pond or marsh, usually in the evening but sometimes even during the day. On arrival, he jumps in the water and swims to what he considers a good position. Only the frog knows why it is a good position, but it probably provides a place to hold onto the vegetation and a place where he can be easily seen as well as heard. Interestingly, it is often the same male that calls first each evening.

He begins to call: ribbit, ribbit, ribbit, a creaky two syllables that carries at least a hundred yards or more on a quiet night. Another frog heads for the pond, either because hopping downhill in a moist environment will lead to water or because it homes in on the first frog. The second frog begins to call, perfectly insinuating its calls between those of the first. The two may sound quite different, so we hear ribbit, rabbit, ribbit, rabbit, ribbit, rabbit.

A third male begins to call, amazingly also able to insert its calls into the soundscape so they can be heard as distinct: ribbit, rabbit, robbit, ribbit, rabbit, robbit . . . the pace is speeding up, and there is no room for a fourth frog, but that one calls anyway. As the chorus swells, the individual voices become less apparent, even though the structure may still be there, but a female approaching the pond can easily distinguish the individual voices.

Females apparently choose males based on the vigor of their songs, and as the evening progresses, more and more males acquire a mate. The male clasps the female and stays with her while she looks for a place to lay her eggs. She finds such a place, lays a cluster of eggs, and the male fertilizes them.

The eggs hatch in a few days, and the tadpoles grow quickly on a diet of plant matter. After a few months, they finally absorb their tails and grow a set of limbs and are then ready to leave the pond. If they survive the year, they will return the following spring, and the pond will resound again with the chorus frog chorus.

Dennis Paulson

CASPIAN TERNS – FABULOUS BIRDS BUT NOT ALWAYS APPRECIATED

2011-05-18T11:58:00.000-07:00

The Caspian Tern (Hydroprogne caspia) is the largest of the world’s terns and one of the most widely distributed. The size of a medium-sized gull, it is a most impressive bird, with its striking silvery-white plumage, black crown, and big red bill. Its vocalizations are no less impressive, a loud rasping call that one could imagine pterodactyls made on their breeding grounds.

Caspian Terns breed on islands in lakes or bays, usually in colonies of hundreds to thousands of birds. The largest Pacific Northwest colony is on East Sand Island, at the mouth of the Columbia River, with about 10,000 pairs. This may be the largest colony in the world. The first eggs are laid in mid April, the first hatching about a month later and the first fledging about a month after that. Thousands of birds are still present in late July, but the colony empties shortly after that.

Most pairs lay three eggs, and when they hatch both adults are kept busy bringing in fish from surrounding waters. They fly well above the water, up to 10 meters or more, and dive when they see a fish near the surface, submerging their body completely. If they succeed, they head for the colony. The young have a high-pitched call, like most young birds, and in and around a colony the constant calling back and forth between parents and offspring brings to light the meaning of the word “cacophony.”

Terns are all fish-eaters, and big colonies of Caspians can only thrive where there are a lot of fish in the nearby waters. The Lower Columbia River is such a place, rich in many kinds of fish at the transition from fresh to salt water. Among them are salmon of several species. After their early growth in fresh water, salmonid smolts descend the river to spend some years in salt water before returning to spawn. It has been estimated that 100 million smolts come downriver each year, most of them released from hatcheries.

The terns, and other fish-eating birds nesting in the same area, are there to receive them. It has also been estimated that the tern colony on East Sand Island accounts for predation on about 5 million of these smolts. Although this is only 5% of the estimated smolt run, it is enough to greatly concern wildlife management personnel in both Washington and Oregon.

In fact, concern seems sufficiently great that the terns have been systematically persecuted. Over the past few decades, Caspian Tern colonies have formed at numerous sites along the Washington coast, and at each of them the birds have been hazed until the colony disbanded. Because they have been chased away from islands, they have tried to nest on rooftops and other humanmade structures, but each time they are discovered, they are soon displaced.

Because a few of the colonies on Columbia River islands are thriving, there are enough excess terns that they are still to be seen and heard flying over all of our coastal waters, but many of them fail to breed because they are not allowed to. Salmonid fishes are of great importance to the Pacific Northwest economy, and Caspian Terns are not; the equation does not favor the terns.

POSTSCRIPT (added 23 June 2011)

The largest PNW tern colony, on Sand Island at the mouth of the Columbia, has been severely disrupted by predators, especially Bald Eagles, and will probably fail this year. Fortunately, the terns are long-lived and will presumably breed next year, but the eagles are proving to be real villains in this case, disrupting colonies of terns and other seabirds severely enough that they pose a long-term threat to the populations of these birds. Anthropogenic changes may have made the situation worse, with a decline in other eagle prey and a reduction of the seabird colonies to few sites.

Dennis Paulson

IT’S SHOREBIRD TIME AGAIN

2011-05-10T16:38:00.000-07:00

Every year in April and May the Pacific Northwest experiences a mad rush of thousands and thousands of shorebirds—sandpipers and plovers—on their way north to their Arctic and Subarctic nesting grounds.

This is nowhere more obvious than around two big coastal estuaries, Grays Harbor and Willapa Bay. These estuaries are extremely productive of the invertebrates that the shorebirds eat. Prey animals are present at very high densities in the mud and sand of these estuaries, for example about 10,000/square meter at Bottle Beach, on the south side of Grays Harbor, one of the most productive areas.

This seems astronomical but pales in comparison with 100,000 individuals/square meter of one species of amphipod in the Bay of Fundy. Nevertheless, it is sufficient density to support the tens of thousands of shorebirds that visit the area for up to a month each spring. Individual birds stay only a few days, fattening up for a flight that may be only 200 kilometers to Roberts Bank in British Columbia or as much as 900 kilometers to the Copper River delta in Alaska, then on to arctic breeding grounds.

The invertebrates that fuel these birds are primarily amphipods and polychaete worms. The amphipods are about 5-6 mm long, and some of the polychaetes are in the same size range. Other polychaetes are called “thin worms,” up to 30 cm long but only 1 mm in diameter! They can be in such high densities as to almost bind the mud together.

The three most abundant species in spring migration are Western Sandpiper, Dunlin, and Short-billed Dowitcher, in descending order. Most of the big flocks you see will include these species. There are many other species present as well, and searching them out gives the observer variety as well as spectacle. Other common species include Black-bellied and Semipalmated Plovers, Greater Yellowlegs, Whimbrel, Marbled Godwit, Ruddy Turnstone, Red Knot, Sanderling, and Least Sandpiper, with numerous others even less common but out there somewhere.

No migration is evident at the beginning of April, but by the middle of the month, Greater Yellowlegs and Short-billed Dowitchers have arrived in numbers. During the last two weeks of the month, all the species move in, most of them in full breeding plumage, and peak right around the first of May. Numbers fall off after that but are still impressive through mid May, and some of the later migrants are present until the end of that month. Species that peak late include Red Knots and Long-billed Dowitchers.

Herb Wilson of Colby College, Maine, found that these hordes of shorebirds had little effect on the invertebrates on which they fed. He erected “exclusion cages” at Bottle Beach, meter-square cages that kept shorebirds out, and after the migration compared the numbers of invertebrates under each cage with the original numbers there and the numbers just outside. He found no fewer invertebrates outside than inside; thus the numbers had not been reduced by the birds.

The spectacle can be seen in feeding areas at lower tides and at roosts at higher tides. The ocean beach itself has throngs of shorebirds on peak migration days, but it is discouraging to see the high levels of human activities (joggers, horseback riders, dog runners, mopeds, pickup trucks) that disturb each flock again and again on a busy weekend day. The birds get back to feeding immediately after each disturbance, and we can only hope that they are able to take in enough nourishment to make it to their next destination on time.

Dennis Paulson

HOLE NESTERS

2011-04-26T14:03:00.000-07:00

It’s late April, and bird migration is in full swing. Among the first birds to arrive are the hole nesters. Some birds make their own holes (primary cavity nesters), but there are others that nest in cavities but cannot excavate them themselves (secondary cavity nesters). The latter are always disadvantaged when it comes to finding a nest cavity, whether an abandoned woodpecker hole or a natural crevice. Basically, there aren’t as many nest sites as there are bird pairs. Even worse, competition is both within and between species for appropriate cavities.

One adaptive strategy in the intense competition for these holes is to be nonmigratory and to defend the nest site all year. It’s probable that the use of their holes for winter roosting has even favored resident status in primary cavity nesters. But interestingly, most of the secondary cavity nesters are migratory. So their best bet is to arrive as early as possible in migration and claim a cavity before anyone else can do so. Because of what must have been strong selection, many of the cavity nesters are among the earliest birds to arrive from the south in spring.

These include Tree (Tachycineta bicolor) and Violet-green (Tachycineta thalassina) Swallows, which arrive in migration in the Pacific Northwest before any of the other swallows. Tree Swallows normally arrive in western Washington in late February, in fact before almost all other migrants. They are competing for tree holes over water, and those are scarce indeed. Violet-greens arrive soon thereafter, looking for tree cavities in forests or niches in cliffs.

Some of these swallows occupy cavities in deserted buildings. That brings up the point that such birds will nest where they can, and human structures, deserted or not, can represent prime real estate if they have any openings into sheltered nest sites.

With our big brains, humans long ago figured out that if cavities were limited, a way to attract hole-nesting birds was to make nest boxes available to them. Thus the well-loved bluebirds have become recipients of so-called Bluebird Trails all over the country. Houses are put out in appropriate habitat at fairly close intervals, usually on fence posts, and they are rapidly accepted by bluebirds (Sialia spp.). Bluebirds and swallows seem always to reach higher breeding densities when provided with nest boxes. Much research on nesting biology has been carried out with the use of these boxes, and widespread declines in bluebird populations have been halted by their use.

There are many other secondary cavity nesters, including Wood Ducks, Buffleheads, goldeneyes, mergansers, kestrels, small owls, Myiarchus flycatchers, some chickadees and nuthatches, flying squirrels, red squirrels, and woodrats. When natural crevices don’t fill the bill, they all depend on the primary excavators, especially woodpeckers. Woodpeckers can be considered keystone species in the forest, as so many species depend on their presence.

Dennis Paulson

BUTTERFLIES IN WINTER

2011-04-19T11:14:00.000-07:00

The majority of butterfly species in our region pass the winter in the larval stage (caterpillars), a smaller number as pupae (chrysalides), and rather few as eggs. But some of our common butterflies overwinter as adults.

They are the last generation of summer, and instead of just dying, as the great majority of adult butterflies and other insects do in autumn, they seek out a protected spot, for example under loose tree bark or in a rock pile, close their wings, and become dormant for the cold season. This can be as long as 4-5 months in the Pacific Northwest.

Adult winter dormancy is characteristic of the genus Nymphalis, butterflies with showy upperwings but very cryptic underwings. These adults are then the first butterflies of spring, even as early as February, as those with a hibernaculum in a sunny spot warm up enough to emerge and fly out to explore the world and, presumably, find a mate and breed.

The Mourning Cloak (Nymphalis antiopa) is the best-known among these butterflies, as its upperside is both spectacularly colored and unmistakable. Breeding on willows and many other common trees and shrubs, it is almost ubiquitous, although absent from dense forest. A freshly emerged Mourning Cloak is often the first sign of spring for a Northwest naturalist, rocketing through a clearing or resting on a sun-drenched log. Don't look for this species on flowers; it prefers tree sap, rotting fruit, and fresh dung!

Milbert’s Tortoiseshell (Nymphalis milberti) is another common species all over the Pacific Northwest. Its upperside is no less beautiful. This species breeds only on stinging nettle, but that plant is sufficiently common that Milbert’s are everywhere. They overwinter in the same sorts of places as Mourning Cloaks and emerge similarly early. Fresh individuals of both species have yellow bands on their wings that fade to white with age. That difference can be seen in the two photos here.

The California Tortoiseshell (Nymphalis californica), also known as Cal Tort to the butterfly cognoscenti, is similar in shape to the other two Nymphalis species but with still another dorsal pattern. It looks rather similar to other butterflies, for example several species of anglewings (Polygonia). The host plants are shrubs of the genus Ceanothus (deer bush, mountain balm), and these are most common from the Cascades east.

This species is of even more interest biologically than the other Nymphalis because of its population cycles. It is absent some years but present in prodigious numbers in others. If you ever drive on a mountain road in late summer and are dazzled by the sheer density of butterflies flying off the road and swirling around the car, they are likely to be this species.

Cal Torts that build up to these numbers undergo massive emigrations, pouring through the mountains and down to the coast, where they are seen flying south with other butterflies and dragonflies. The points of origin and destination of these migrating butterflies are unknown, but the movements may be a consequence of host plant availability, population pressures, and/or weather conditions. This would be a good species to study in depth.

Dennis Paulson

SOME SNAKES ARE SHARP, SOME ARE DULL

2011-04-12T14:45:00.000-07:00

This is most apparent if you look at the ends of their tails.

The Sharp-tailed Snake (Contia tenuis) epitomizes the sharp end of the spectrum. The tip of its tail, really the last scale on the tail, is quite sharply pointed. This small and secretive snake is usually found under logs or rocks, and it presumably comes out at night, when it hunts for its primary prey, slugs. Oddly, one of the most commonly observed prey species is an introduced slug, and one wonders what they ate before the introduction!

It may be that the sharply pointed tail tip is handy for subduing slimy prey, but it also has been speculated that it may be used against predators (a snake may press it into the hand of a human captor) or even as an aid in burrowing. All pure speculation, of course, but we assume there must be some adaptive function of this prickly tail.

It has also been suggested that the banded pattern on the snake’s underside, sometimes exposed, may mimic the banded pattern of several millipede species of the area. As the millipedes are toxic and distasteful, some Sharp-tailed Snakes may escape predation by this mimicry.

Few people see this interesting snake, as its range is very restricted in the Pacific Northwest, and it appears to be active only for a relatively short time in spring and fall, when it is warm enough for reptile activity yet cool and moist enough so this small species isn’t stressed by low humidity. April and September are good months to look for sharp-tails by looking under objects on the ground that may serve as hiding places. Be sure to replace them carefully.

Rubber Boas (Charina bottae) are at the other end of the spectrum, with an extremely blunt tail for a snake. One of the consequences of this is that it is difficult to distinguish the head end from the tail end, and this may be the whole point, as it could be an effective anti-predator strategy. A snake captured by the wrong end might be more able to escape, and, if inclined, might even bite the predator. The latter seems unlikely, as these snakes are extremely docile, at least when picked up by a human.

Rubber Boas are much more common and widespread in the Northwest, usually associated with open conifer woodland. They are active all summer and take a wide variety of prey, mostly small mammals but also other vertebrates. They are active at night during much of the summer, but on cooler days especially they may be seen out and about. Otherwise, you look under rocks and logs, just as you would to find Sharp-tailed Snakes. A fortunate naturalist might find both of them together!

Dennis Paulson

SPRING IS THE TIME FOR GROUND SQUIRRELS

2011-04-12T11:40:00.000-07:00

It’s hard to conceive of a species spending most of its life asleep, but that’s the case for the spring ground squirrels.

Ground squirrels feed on herbaceous vegetation, and many of them are active throughout the summer and then hibernate during the winter. Some ground squirrels, however, live in arid deserts or grasslands in which lush growing vegetation is present only during the spring or during a summer rainy season. These species are active only during that time, so they are active above ground for only about a third of the year.

Two species that exemplify this scenario are the Washington Ground Squirrel (Spermophilus washingtoni) and Piute Ground Squirrel (Spermophilus mollis). Both are small, short-tailed species. Piute Ground squirrels occur in a limited area of sagebrush steppe in southern Washington between the Cascades and the Columbia River. Washington Ground Squirrels occur east of that river in the Columbia Basin. Both species have declined substantially in recent years as their habitat has been lost to agriculture.

Belding's Ground Squirrel (Spermophilus beldingi) is a slightly larger and more southerly species of the high desert in eastern Oregon and northern California. It has adapted very well to agriculture, so it is still abundant, but its life history is much like that of the other two.

Washington Ground Squirrels have litters of about eight young. They are born in late winter and emerge from their burrows about a month after the adults. A visitor to a ground squirrel colony around the beginning of April is treated to the sight of playful young on all sides, while the adults go about the business of serious eating.

After a few months of activity, with an abundance of fresh salads on the daily menu, first the adults and then the juveniles retire back into their burrows and spend the summer in a state of torpor called aestivation. Aestivation then grades into the usual winter hibernation. The longest an individual of these species spends above ground is about four months. One adult Washington Ground Squirrel in captivity was dormant for 244 days.

Juveniles grow to adult weight in two months after leaving the burrow. All individuals begin to deposit fat 6-8 weeks after emerging and end up with lipids comprising about 65% of their body weight when they go into the burrow for good. They then live through the summer, fall and winter on the fat deposited during the spring.

High temperature and low humidity are stressful on any animal, and as there is no new growth on the plants they favor, the spring-active ground squirrels have no source of water during the summer; thus aestivation. Aestivation is an adaptation for survival in hot, dry climates, just as hibernation is an adaptation for survival in cold climates. These small animals use both of these strategies, surviving by the fine tuning of their seasonal activity to their climate. How will global warming affect them?

Dennis Paulson

THE BIRDS THINK IT’S SPRING

2011-03-22T17:10:00.000-07:00

This is the time of year when our resident birds begin to sing. Already I have heard Anna’s Hummingbird, Bewick’s Wren, American Robin, Varied Thrush, European Starling, House Finch, Song Sparrow, and Dark-eyed Junco singing around my house. On the other hand, the vast majority of migrant species have not arrived yet, and those residents that are singing won’t be breeding until some time in April.

Why don’t all birds breed at the same time? Well, an easy explanation for raptors is that their incubation periods are long, so it behooves them to breed before many other species, so they have eggs hatching at a time when food resources are high. As it turns out, the eggs of the early breeders hatch at a time when many local mammals are weaning young.

Some species, for example raptors such as Barn and Great Horned Owls and Red-tailed Hawks, have already begun their breeding cycles. A Northwest pair of Red-tailed Hawks could have a complete clutch of three eggs laid by March 20. The first egg would hatch in mid April, and young would be ready to leave the nest by the end of May.

The bird-eating accipiter hawks (Cooper’s, Sharp-shinned) begin to breed later than the mammal eaters, because the supply of naïve young birds doesn’t really kick in until May or June. A Cooper’s Hawk pair that lays the first egg of a clutch of four on April 15 would expect the first young to hatch on May 20 and the first young to fledge about a month after that. By the end of May there are great numbers of young, naïve birds in the surrounding woodland that can provide prey for a family of Cooper’s Hawks.

A Barn Owl that laid her first of six to eight eggs on March 10 would see the first young hatch on April 10 and fledge in about two months. By hatching time, great numbers of young voles would have emerged from their grass nests to forage in their myriad runways, and the parents can find plenty of protein for their growing young. Furthermore, a just-fledged owlet should have no trouble detecting and catching those furry snacks.

Mammal-eating owls such as Barn and Great Horned breed early, but insect-eaters such as Western Screech and Burrowing Owls breed later for two reasons. First, incubation and fledging periods are shorter for smaller birds, so there is no reason to start so early. More importantly, their prey does not become active until ambient temperatures allow activity. So these owls are laying their eggs in April and even May.

A Burrowing Owl clutch of eight eggs might be completed on April 15, when incubation would ensue. The eggs would hatch around May 15, and the young would be ready to leave the burrow by the end of June, when insects and lizards abounded in its nesting territory.

So the eggs of the mammal eaters hatch about a month before the eggs of the bird and insect eaters, just as predicted. Not only the wonderful adaptations of living organisms, but also their exquisitely fine tuning, never fail to impress me.

Dennis Paulson

BIG BLACK BIRDS WITH BULGY BEAKS

2011-03-07T12:56:00.000-08:00

These are the scoters, three species of ducks we are fortunate to see in the Pacific Northwest every winter. The males are black with bright head markings, the females mostly dark brown. They breed in Canada and Alaska and winter along most of the temperate coasts of the United States. They are mostly confined to salt water in the nonbreeding season, although wintering numbers on the Great Lakes have increased because of the proliferation of zebra mussels there.

The Surf Scoter (Melanitta perspicillata) is the most common of the three scoters wintering in the Pacific Northwest. While all three scoters include a variety of marine invertebrates in their diets, they seem to be bivalve specialists. The heavy bill of a Surf Scoter provides it with strength to pull mussels loose from their attachments to rocks and pilings. Accordingly, Surf Scoters are common where there are large beds of mussels, and that includes a lot of territory in this region.

Surf Scoter courtship displays are fun to watch. The male flies a short distance with loudly whistling wings, then slides to a stop on the water with both wings raised high. How could a female not be impressed? Like other ducks, they pair during the winter and fly back to the breeding grounds together. Most males probably don’t breed until they are two years old, and younger males can be distinguished in winter by less brightly colored bill and often smaller white head patches.

White-winged Scoters (Melanitta fusca) appear to be more locally distributed than their Surf cousins. They are most common in bays with sand substrates, where clams are much more common than mussels, surely indicating a food preference. The White-winged is a bit bigger than the Surf and is our largest duck. The big white wing patches are prominent in flight but may be hidden on a resting bird. Note the difference in feathering on the bill of the two species, useful when identifying juveniles, which look very similar.

The Black Scoter (Melanitta americana) is the least common and most locally distributed of the PNW scoters. Its head shape is more like that of other ducks, presumably indicating it is less extremely adapted for bivalve pulling. As in the Surf Scoter, the male wings whistle in flight.

Male scoters see their mates on a nest on the breeding lake and then head for the coast in what is called molt migration. Female Surf Scoters follow the males after they raise their young, but female White-wings undergo this molt on the breeding grounds. The molt migrants arrive at their destination and begin their body and wing molts. They are flightless during wing molt, so they need to be somewhere with abundant food resources for that period. After completing molt, many continue farther south along the coast.

Scoter migration is dramatic on the outer coast, where flock after flock of Surf Scoters pass by just offshore, heading south in September and October and north in April and May. Smaller flocks of White-winged Scoters are interspersed, but you’ll have to look long and hard for the much smaller numbers of Black Scoters. Migrants of many other seabirds, in flocks and by themselves, add to the thrilling experience of a few hours spent on an outer-coast point.

Dennis Paulson

THE LARGEST SONGBIRD

2011-02-22T14:49:00.000-08:00

This is not a bird that you think of when you think of songbirds, but in fact that’s exactly what a Common Raven (Corvus corax) is. Along with all the other members of its family, the Corvidae, it is a bona fide member of the suborder Oscines, the “songbirds” of the order Passeriformes.

Although no one would ever accuse a raven of singing, its vocalizations are varied. Most of the time we hear ravens giving their single or multiple somewhat musical croak, lasting for a second and with distinct harmonics. This is apparently a location call, making other ravens aware of the bird’s presence, and it is most commonly heard from birds moving over the landscape. That call is the epitome of raven sounds, but the species expresses a wide variety of other calls in varied circumstances. They are similar enough so that elaboration of their function has been difficult.

The Common Raven is also the widest-ranging corvid and a fine example of a successful species. It is distributed throughout the Far North, including Greenland and Iceland, and all across the northern hemisphere south to Nicaragua, northern Africa, northern India, and central China. Populations occur in all terrestrial habitats except rain forest.

Ravens are true omnivores, taking just about anything edible they can find in their environment. Because they are so large, they can be effective predators on a wide range of animals up to the size of pigeons. They spend much time hunting voles where those rodents are abundant, and a vole is just the size to be swallowed in a single gulp.

During breeding season, any bird with a visible nest is in danger from sharp-eyed ravens. Pairs fly over the tundra, and when a shorebird such as a Whimbrel spots a raven coming, it will leave its nest to begin mobbing actions. Unfortunately for the bird, the raven’s mate, off to the side, may have seen exactly where the nest was located.

Garbage dumps are favored hunting grounds for ravens, which may visit them in large numbers. A thorough analysis of their “prey” there is not for the faint of stomach. Similarly, well-traveled roads with their road kills furnish a linear cafeteria for ravens, especially in the morning when they can often be seen systematically searching their length. The guaranteed presence of carrion (everything dies eventually) may be one of the factors that allow ravens to live just about anywhere, from tundra to mountain forest to desert.

Ravens are well-known to accompany wolves and other predators on hunts for the chance that food scraps may await them. They have been suspected of purposefully attracting both wolves and human hunters to moose and caribou.

Ravens mate for life and are commonly seen in pairs. They are superb flyers, soaring like hawks or plummeting through the sky in spectacular dives. A typical raven antic is to do a half-roll or even a full barrel roll in flight, and they have been seen to fly upside-down for considerable distances.

As should be evident by now, ravens are near the top of the list of brainy birds. Corvid intelligence is well documented, and books on ravens by Bernd Heinrich (Mind of the Raven and Ravens in Winter) and John Marzluff (In the Company of Crows and Ravens and Dog Days, Raven Nights) present this documentation as fascinating reading.

Pet ravens are especially playful birds, especially young ones, and whether their varied antics (sliding downhill, hanging upside down, dropping and catching objects while in flight, pecking dogs on the tail) are all related to survival is debatable. (Don't try this yourself; ravens are a protected species). One certainty is that raven watching will never be boring.

Dennis Paulson

FLOCKING BIRDS

2011-02-17T10:11:00.000-08:00

A question that is often asked is why birds flock. And why do some of them form mixed flocks?

It is certain that birds flock for evolutionarily sound reasons: to avoid predation and to find and capture prey.

By flocking, birds have a better chance to avoid predators than when they are by themselves. First, with more birds together, there is a higher level of alertness, as individuals are likely to be looking in different directions, and not all of them will have their heads down at the same time. In fact, it has been found that birds spend more time feeding and less time looking around when in flocks. Some shorebirds that feed by constantly probing the substrate, for example godwits, may flock with other species that forage with heads up, for example curlews, for the added vigilance.

Second, when birds fly in flocks, they make it more difficult for aerial predators such as falcons to catch them, because the falcon has to concentrate on a single bird, while a group promotes confusion. Furthermore, a bird in a flock of 20 has only a one in 20 chance of being caught, whereas a bird by itself has a statistically more serious problem. When a Bald Eagle flies over a flock of coots, they scatter in all directions.

Third, birds in flocks can actually intimidate predators. Starlings form a swirling superentity and dive on any hawk that approaches them; the tactic works quite well.

There are other advantages. Birds may discover food by associating in groups. Vultures and gulls roost in flocks, then spread out to feed while keeping a distant eye on one another. A vulture that drops to the ground is at the center of a contracting circle of birds heading in its direction. Gulls and terns have been attracted from boats by a handkerchief thrown in the air, simulating a bird dropping to the water.

Birds may also flock to capture prey more effectively. Pelicans in a line drive fish in front of them. Auklets surround a herring school and control its movements just as border collies herd a flock of sheep (why don’t falcons do this with shorebirds?).

Presumably birds form mixed-species flocks for the same reasons. If a flock of 100 is more effective than one half its size, then it makes sense for 50 blackbirds and 50 starlings to forage and fly together. For the most part, birds of similar size and habits flock together, so you’re unlikely to see a mixed flock of murres and juncos.

One of the most commonly seen mixed flocks is a winter feeding flock. In this area, it usually contains chickadees of one or more species, often Red-breasted Nuthatches, and sometimes Golden-crowned and/or Ruby-crowned Kinglets. The flock may be joined by a Downy Woodpecker or Brown Creeper or Townsend’s Warbler or Hutton’s Vireo. By moving through the woods together, these birds may help one another spot particularly good feeding areas, and they are surely more alert to predators as a group than if they were foraging individually.

I wonder if it’s possible to explain any of our own social behavior by this reasoning. Or can we explain bird behavior by what we know of our own? Perhaps some birds flock just to check out members of the opposite sex for the next breeding season.

Dennis Paulson

THE GULLS OF PUGET SOUND

2011-02-08T10:23:00.000-08:00

Gulls can be best viewed where we concentrate them, anywhere from fast-food restaurants (French fries are a favorite) to waterfront parks (white bread a staple of the menu) to a meat- or fish-processing plant where they relish the offal, awful as it is. For the most part, the large gulls dominate these assemblages, although if there are few of them, smaller species may be in attendance. The smallest species, Mew and Bonaparte’s Gulls, have different feeding habits and are not part of these spectacles.

As pointed out in a previous blog, the Glaucous-winged is the most common and certainly most ubiquitous gull in Puget Sound. It and the much smaller Mew Gull are the ones you see everywhere throughout the winter. During spring and fall migration, large numbers of Bonaparte’s Gulls appear, and during fall migration there are even larger numbers of California and Heermann’s Gulls.

In addition to these five species, several others are seen in much smaller numbers. Thayer’s and Western Gulls are uncommon during winter, Herring and Ring-billed Gulls even less common. After these nine regularly occurring species, any other species is much rarer. This discussion will concern itself with adult plumages; the immature plumages are usually quite different.

Heermann’s Gulls (Larus heermanni) are medium-sized and stand out by their entirely gray body and black tail; the bill is red, the legs black. In breeding season, the head is white, but we don’t see it in that plumage, as it is a fall visitor from breeding colonies in Baja California. It is more common in the northern part of Puget Sound, mostly in September and October.

Bonaparte’s Gulls (Larus philadelphia), usually seen in migration but remaining for the winter in small numbers, are easily distinguished by their small size, black bill and red legs, and extensively white wingtips. In breeding plumage, they have a black head. They tend to be in flocks, sometimes large ones, and they often feed along convergence lines, or “tide rips.”

All the other gulls have gray mantles, yellow bills, and white heads, bodies, and tails in breeding plumage. Mew Gulls (Larus canus) are the smallest of these, not much larger than Bonaparte’s. Adults have thin, almost pigeonlike, yellow bills and yellow legs. The eyes are brown, the mantle (back and upper surfaces of wings) medium gray. In nonbreeding plumage, the head and neck are strongly marked with gray. The extreme wingtips are black, with large white spots that furnish a characteristic field mark. Like Bonaparte’s, this species is most commonly seen feeding along convergence lines but is common and widespread throughout the region in winter.

The next larger is Ring-billed (Larus delawarensis), with mantle paler gray and contrasty black wingtips. The white tip spots are smaller than in Mew. The bill is yellow with a black ring, the legs yellow, and the iris yellow. This freshwater species is only occasionally seen on Puget Sound but is noteworthy for its very contrasty markings.

A bit larger, the California Gull (Larus californicus) is patterned about like the Ring-billed but has a darker gray mantle, like the Mew, and brown eyes. Note both mantle color and eye color alternate with progression from Mew to Ring-billed to California. The yellow bill features a black spot in front of the red spot characteristic of all the larger species.

The rest of the regularly occurring gulls, larger yet, have yellow bills with a red spot on the lower mandible and pink feet. Thayer’s (Larus thayeri) and Herring (Larus argentatus) are very similar, both with pale gray mantles and less black at the wingtips than either California or Ring-billed. Herring always has a yellow eye, Thayer’s usually a brown eye, but the eye is pale in some individuals. Thayer’s is slightly smaller, with a distinctly smaller bill and more rounded head shape. The wingtips of Herring are blackish above and below, while in Thayer’s, there is not only less black but it shows up scarcely at all from below. So wingtips black above and pale below are characteristic of Thayer’s.

Finally, the two largest species, Glaucous-winged (Larus glaucescens) and Western (Larus occidentalis), differ primarily in mantle and wingtip color. In Glaucous-winged, the mantle and wingtips are gray and darker gray, in Western dark gray and black, respectively. Very different-looking birds, they unfortunately (for the birdwatcher) hybridize freely in the Puget Sound area, and the hybrids come in all shades of gray. These have been called “Olympic gulls,” and they complicate field identification. The wings are always more uniform than they are in Herring and Thayer’s, in which the light gray mantle and black wingtips contrast strongly.

Western Gulls have slightly larger bills than Glaucous-winged and are more likely to have yellowish eyes. The skin around their eyes is yellow, the same in Glaucous-winged is pink. But again, the hybrids complicate the issue. Western is much less common in Puget Sound, but there are pure Westerns along with the hybrids. A pure Western usually retains a white head throughout the winter and doesn’t acquire a black smudge on the red bill spot as does Glaucous-winged.

See the Slater Museum’s gull web page (http://www.pugetsound.edu/academics/academic-resources/slater-museum/biodiversity-resources/birds/identification-of-pacific-nort/) for more images and further information on identification.

Dennis Paulson

THE COMMON SEAGULL

2011-02-01T14:26:00.000-08:00

Seagull? Everyone knows what a seagull is, but why do we use that name for them? They are gulls, GULLS. We don’t have “seaducks” or “sealoons” or “seaterns,” so why “seagulls?” I don’t know, but I’ll never stop asking that question. Although all of them visit the sea for at least part of the year, more than half of the gull species breed on fresh water.

On Puget Sound, there is one very common gull, the Glaucous-winged (Larus glaucescens). In winter, most of the large gulls you see are Glaucous-winged, just as most of the small gulls are Mew Gulls. A moderate variety of species make up the other few percent.

Although in winter they wander inland to near-coastal freshwater lakes and well up the larger rivers, Glaucous-wings are basically marine birds. They breed throughout the protected marine waters of the Pacific Northwest in good-sized colonies on islands and scattered as single pairs at ferry docks or on rooftops. On the outer coast, the Glaucous-winged is replaced by the Western Gull as a breeding species.

Each pair nests in a scrape on the ground, lined with grass, twigs, and anything else that can be found in the limited nesting territory. The female usually lays three eggs totaling about 10% of her body weight, the last egg laid a bit smaller than the others. Both sexes alternate incubation for a period of about 27 days. Hatching takes a surprisingly long time, 2-3 days from pipping (first crack appears) to completely out.

The adults quickly begin to forage for the young, foraging trips lasting several hours. Prey items are brought about 10 times/day to a nest of three young. The young grow rapidly and are able to fly at about six weeks of age. They typically leave the colony at about eight weeks but are fed by the adults for some time afterwards, even well away from the breeding site. Young birds will beg from their own parents and other adults well into the winter, with diminishing returns.

Fully fledged juveniles are brown, coffee-with-cream colored with fine markings on most feathers. The wings and tail are very slightly darker than the body feathers and relatively unmarked. The bill is black, the legs dull pinkish. Limited molt begins during the fall, and the brown feathers of the back are replaced by gray.

Large gulls, including this species, seem to molt during a large part of the year, so plumage changes signaling a transition from immaturity to maturity occur not only between years but within years. The largest gull species take about four years to reach maturity, and their plumage changes throughout that time.

A typical first-year gull is brown, like the Glaucous-winged described here. By the time it is a year old, certain changes are evident in its plumage. Typically the mantle (= back) has become some shade of gray, and white feathering is increasing on the head and breast. The bill becomes pale (pinkish) at the base. The rest of the body and wings and tail look about the same.

By the second spring (about 20 months old), much more of the head and underparts are white, the bill has more pale color at its base, and gray feathers are appearing in the wing coverts. The wings and tail are still the same shade of brown, although both have been molted once.

By their third spring, Glaucous-winged Gulls look much more like adults. The bill has dark markings restricted to the tip and may be starting to turn yellow. Most of the head and body feathers are white (except for dark streaks and smudges on the head and neck). The wings are largely gray, the primary feathers with slightly darker tips and restricted white spots at the very ends. The tail is white, with or without gray spots toward the ends of the feathers.

One of these birds could easily be mistaken for an adult, but the white primary tips are more restricted, there is often a dusky wash across the upper surface of the wings, and the bill usually has a dark tip or subapical ring. there is much variation in plumage at this age. Some individuals look more like two-year olds, others more like fully adults. A small percentage defy categorization.

When the gull is mature, it has an entirely white body and tail and gray mantle, with slightly darker wingtips with white spots in them. The iris is brown, the bill bright yellow with a red spot on the lower mandible, the feet pink. The circumorbital skin is also pink. In nonbreeding plumage, the head and neck are suffused with dusky markings, and a black smudge appears on the red bill spot.

Back in the 1950s, a small group of these gulls from the Protection Island colony were raised to maturity in captivity by Zella Schultz of Seattle Audubon Society, and the variation within any given year class was surprisingly great. This is presumably because different birds have different hormone levels and apparently molt at slightly different times and/or with different degrees of completeness.

That tremendous variety of gulls that we see out there is caused, at least in part, by the gradual plumage change from young to adult in each species. Learn it in the Glaucous-winged Gull, and you will feel a sense of satisfaction at having made complexity somewhat simpler.

Dennis Paulson

THE HAWK OF THE OWLS

2011-01-18T14:09:00.000-08:00

When you first encounter a Northern Hawk Owl (Surnia ulula), you will understand why it has two different types of raptors in its name. Clearly an owl because of that big head and forward-facing eyes, nevertheless it has the rakish look of a hawk about it, with long tail, rapid flight, and – of course – diurnal habits.

One of these birds spent the winter of 2010-2011 on Westham Island in southwestern British Columbia, delighting birders and nature photographers by the hundreds. Because of their open perching habits and tameness, Hawk Owls are readily detected where they occur, so it is likely that at least some of the few individuals that make it to peripheral wintering areas are found as observers scrutinize the winter landscape. In my case, it was a wonderful way to start the year - and on a beautiful sunny day!

In the Pacific Northwest, we don’t get veritable invasions in winter, with dozens of Hawk Owls showing up like they do in the Great Lakes region. Nevertheless, at least a few birds make it down to Washington in most winters, and with increasing knowledge of where to look for them, more have been seen in recent years. Breeding has been confirmed at Manning Provincial Park, just north of the border in British Columbia, and suspected at Harts Pass in Washington.

Hawk Owls perch, usually at the very top of a tree or other conspicuous perch (often on utility wires in this day and age), and survey the surrounding semiopen landscape for their prey. Their primary prey is voles, but they are willing to take anything they can subdue from a long list of mammals up to the size of hares and birds up to the size of grouse.

Hawk Owls are not modified like many other owls for auditory hunting. Their two ears are symmetrical, and they don’t have a well-developed facial disk. They must have good hearing, however, as they are occasionally seen to plunge into snow to capture a vole. With long tail and short, rounded wings, they hunt somewhat like accipiter hawks, detecting prey visually and dropping from a perch to move at high speed with rapid wing beats. Most prey is captured at fairly close range, but their distant vision is excellent.

There are other diurnal owls. Most pygmy-owls hunt during the day, small birds their primary prey. Snowy Owls and Burrowing Owls are conspicuous features of open landscapes, although both hunt at night as well. Short-eared Owls can be seen during the day, but much of their hunting is at dusk. The same is true for Great Gray Owls. Hawk Owls, conspicuous on their perches all day long, also tend to hunt more in the afternoon, so hunting in dim light seems to be hardwired in owls.

Bear in mind that owls of the Far North must be able to hunt both day and night, as the days are so long in summer, the nights so long in winter. Fortunately for them, voles are active day and night.

Like many other owls, Hawk Owls nest in natural cavities, for example at the hollow tops of broken-off snags, and holes abandoned by woodpeckers. Their clutch size varies from 3-13 eggs, with a mean of about 7. It is a large and variable clutch size, as is the case with several owl species that seem to depend on voles and lemmings for their reproductive success.

Keep your eyes peeled for the owl that acts like a hawk!

Dennis Paulson

THE ELEGANT DUCK

2011-01-12T13:28:00.000-08:00

When we think of ducks, we may think of familiar white waddling barnyard Pekins, but in fact these waterfowl are among the most strikingly colored birds. Some of them are downright gorgeous. Look at a Wood Duck if you like brilliant iridescence. How about a Long-tailed Duck for a pleasing pattern of black, brown, and white? Or if swatches of pure color attract you, peruse a Cinnamon Teal. Of course it is the males you will be looking at, as females are generally brown; not that they aren’t beautiful in their own ways.

The Northern Pintail (Anas acuta), not the most brightly colored of ducks, is surely the most elegant. The long, swanlike neck of the male of this species contributes to the look of elegance, as do the long, sweeping central tail feathers. The subdued gray and white body and rich dark brown head add patrician colors to the attractive shape. Even the females, somewhat smaller than the males, have longer necks than those of other ducks.

Why the long neck? Well, dabbling ducks often feed by upending in shallow water, their tail up in the air and their head and neck submerged to sample underwater fare such as leaves, buds, and seeds of aquatic plants and a great variety of invertebrates. You can only reach so far with an average-length neck, and over time pintails just outreached the competition by evolving that long neck. By feeding in water too deep for their near relatives, they presumably were able to take advantage of resources unavailable to the others.

But it must be added that most of the feeding done by pintails is in very shallow water or on land, where they take seeds from sedges and grasses. On their wintering grounds, they are very common among the dabbling ducks that feed on marine invertebrates on mudflats as the tide goes out. The long neck also serves them well in those situations, allowing a foraging bird to reach all around it. This adaptable species is one of the most abundant ducks in western wetlands.

As in other temperate-zone ducks, pair bonds are formed in fall and early winter, and you can expect to see pintail pairs from then on until the female has laid her 5-10 eggs. Male courtship consists of ritualized displays and vocalizations, with head up, bill down, and tail up prominent components. That long, slinky tail is surely impressive at this point. Females are impressed by both the intensity of courtship displays and the constant attentiveness of the courting male. Some of the choice may also involve appearance, males with more colorful scapulars and whiter breasts preferred.

Because mortality is heavier on females than males in most ducks, there is a surplus of males in late winter and spring after all the females are paired up. In this and other dabbling ducks, it is common to see groups of males in pursuit of a single female. These pursuit flights can involve up to a dozen males – although usually just a few – and last for many minutes. They may end with a forced copulation when the female is forced down on land, or the female may “escape” only to be harassed by other males that spot her. The female may have to be mated to avoid this.

Prime pintail breeding habitat is a shallow marsh. Because such marshes are subject to disappearance during any extended drought, they come and go in the landscape, and so do pintails. During wet years, they do well, and their numbers increase. During widespread droughts, the opposite is the case. Breeding populations wax and wane and have varied from about 2 million to about 10 million birds in recent decades.

Dennis Paulson

WASHINGTON CHIPMUNKS

2010-12-21T11:45:00.000-08:00

Mammal watching has never achieved the popularity of bird watching for at least one reason: most mammals are nocturnal. Not only are most of them small and brown, but you can’t even see them! Mammalogists survey mammals by trapping them, netting them, looking for their tracks and scat, etc. Their survey methods don’t usually include walking around with a pair of binoculars on a nice, sunny day in spring.

But there are exceptions. Some mammals are much more visible than others, primarily because they are diurnal. These include many of the large grazing and browsing hoofed mammals (ungulates), the cute pikas of western mountains, and the squirrels. The Pacific Northwest is abundantly provided with squirrels, encompassing the taxonomic range of the squirrel family: flying squirrels, tree squirrels, ground squirrels, marmots, and chipmunks.

Chipmunks come close to being birdwatchers’ mammals. They are active during the day, with an emphasis on the “active,” they are brightly marked, they are territorial, they vocalize frequently, and they come readily to bird feeders. They vary from very shy to very inquisitive, even tame where they encounter people regularly. They are still basically brown, but their conspicuous stripes make them easily recognizable as chipmunks.

These small squirrels are usually associated with rock piles and fallen logs, where they nest. They forage on the ground and in shrubs, sometimes ascending well up into the trees. Hyperactivity describes them best, as they move jerkily along with tail cocked up into the air. When disturbed, they dart into cover, appearing some distance away for another look at the disturbance.

Basically seed eaters, chipmunks will take anything that comes along, including fruits, fungi, and arthropods. They are accomplished nest robbers. taking bird eggs whenever they can find them. During the fall, they busily gather seeds in cheek pouches and cache them in their protected nests. They can then hole up for the winter and feast on these caches without leaving their protected shelter. Caches can contain tens of thousands of seeds.

Most western states have several species of chipmunks; Washington has four. The most common and widespread species in Washington is the Yellow-pine Chipmunk (Tamias amoenus), so named because it is common in the ponderosa (or yellow) pine zone east of the Cascade Mountains crest. Absent from the dense forest of the western lowlands and mid elevations in the mountains, it is again common in the subalpine-alpine zone of the Cascades and Olympics. It is easily seen by hikers in the high country and drivers through almost any of the interior national forests. It is at home in trees, ascending high into pines to forage for the seeds.

The Red-tailed Chipmunk (Tamias ruficaudus) looks about like the Yellow-pine but is slightly larger and longer tailed, and the tail is more intense reddish below. It occurs in the mountains of far northeastern Washington, in Stevens, Pend Oreille, and northern Spokane counties. Its habitat zone is the montane conifer forest and open subalpine zone above that, mostly above the elevation range of the Yellow-pine.

This species would not have been separated from the Yellow-pine but for its copulatory organ. Rodents have a bony structure in the penis called the baculum, and this structure differs among different species of chipmunks. That of the Red-tailed is distinctly longer than that of the Yellow-pine. I have not read of any structural characteristics that differentiated the females!

The largest Washington chipmunk is the Townsend’s (Tamias townsendii), restricted to the forested western lowlands and similar dense habitats up to treeline in the Olympics and Cascades. It occurs in both forested and open (e.g., clear cuts) microhabitats. It is not found in the more open ponderosa pine woodlands below the wet conifer forests on the east side. In addition to being larger and darker, not as brightly marked, it differs from all the other species in not having a clearly defined dark stripe extending from nose to eye. This and the Yellow-pine often occur together in ecotones between open alpine or ponderosa pine habitat on one side and dense conifer forest on the other. Washington Pass is one such location.

Finally, the Least Chipmunk (Tamias minimus) is restricted to sagebrush habitats in the southern part of the Columbia Basin. It is a smaller species, generally paler and grayer than the others, with the back stripes brown instead of blackish and very little reddish or brown color anywhere. It overlaps with Yellow-pine where sagebrush, grassland, and ponderosa pine come together. Least Chipmunks occur at higher densities than the other species, and one place to see this is at the Ryegrass rest stop east of Ellensburg on eastbound I-90. It is full of Least Chipmunks most of the year, gathering by the dozens at the feast of sunflower seeds put out by DOT employees.

There is also a pair of chipmunk lookalikes in Washington. The Cascade Golden-mantled Ground Squirrel (Spermophilus saturatus) is found throughout the Cascades, in both semiopen conifer forest and alpine meadows. The Golden-mantled Ground Squirrel (Spermophilus lateralis) occurs in similar habitats in the Blue Mountains and, less commonly, the mountain ranges east of the Okanogan River. Both are larger than chipmunks, with an unstriped golden-orange head. Most ground squirrels eat leaves rather than seeds, but these species are more chipmunk-like in their diet.

Dennis Paulson

DIVING BIRDS

2010-12-17T15:55:00.000-08:00

Many kinds of birds dive for a living. Not from a diving board, but from the air or the water surface. Some of these birds fly over the water, see potential prey, and dive from the air to attempt capture. These birds are called plunge divers. Gulls plunge into the water to about their own body length and retrieve prey from near the surface. Terns, some pelicans, tropicbirds, and boobies dive from above the surface, the first three penetrating farther into the water column than the gulls do. Boobies (and their close relatives the gannets) penetrate well below the surface and actively chase fish underwater.

Many other birds dive from the water surface, including loons, grebes, cormorants, alcids (puffins and their relatives), diving-petrels, some shearwaters, coots, and many ducks. In this discussion let’s look at this group, so-called surface divers.

All diving birds have feet that are modified for swimming at the surface, and these same feet serve them well for underwater propulsion. The typical swimming foot is that of a duck, with the three forward toes joined by webs. The hind toe is much reduced. Among the diving birds, these webbed feet also characterize loons, gulls, terns, shearwaters, diving-petrels, and alcids (this last group lacks a hind toe).

A variation on this is to have the hind toe lengthened and all four toes connected by webs. This characterizes cormorants, pelicans, boobies, and tropicbirds. Finally, instead of webs, some birds have each of the toes, including the hind one, provided with large, flat lobes that are equally efficient in propelling the bird forward. Divers with lobed toes include grebes and coots.

Surface divers vary quite a bit in how they dive and how they locomote under water. Most of them just put their head down, slide under the surface, and propel themselves downward. Although the feet stroke alternately while swimming on the surface, when underwater they stroke in unison, like a pair of oars, and they are held out to either side. This must use different sets of muscles than those used for swimming on the surface. Smaller birds such as grebes, coots, and small cormorants may jump up into the air to enter the water with more momentum.

One group of birds exhibits a real variation in this theme. The alcids are wing-propelled surface divers, using their wings to swim just as if they were flying underwater. As they go below the surface, you can see their wings already open as their means of propulsion. In the guillemots, which feed on bottom fish, the feet are used along with the wings, but in murres and puffins and others that feed on midwater fish and krill, they are held behind and not used at all. The southern-hemisphere diving-petrels, related to true petrels, also use this method of propulsion, as do penguins. Not able to fly, penguins are the most highly modified birds for underwater living.

Scoters and some other sea ducks such as Long-tailed Ducks open their wings as they dive, easily seen. They may use them as diving planes underwater or may actually flap them just as alcids do. For the most part, diving birds surface just by stopping their underwater propulsion and, like a cork, popping back up to the surface. They go headfirst, the most streamlined way to go. Alcids sometimes swim actively upward and penguins always do.

Although you would think that fish are the fastest swimmers in the sea, the most amazing thing about diving birds to me is that they can swim faster than the fish, presumably a necessity if they are to catch them! Both animals streak through the water, and just like a smaller bird trying to escape from a hawk, the fish may or may not escape.

Still photos of birds swimming underwater are very hard to come by, although YouTube and other such online video sites show a variety of birds swimming underwater, very often misidentified (grebes and alcids called “ducks”). Notwithstanding these few videos, we have much to learn about how diving birds forage underwater.

Dennis Paulson

CRANES AND HERONS

2010-11-18T09:25:00.000-08:00

Many people call the large, gray, long-necked and long-legged birds we see wading near shore “cranes.” But they are not. They are herons. The Great Blue Heron (Ardea herodias) is in the heron family (Ardeidae). It feeds by standing or slowly walking on its long legs, sighting prey, and then capturing it with a lightning-fast strike of the bill. The head is brought back and the prey swallowed, usually headfirst.

Prey that is not killed by the strike is manipulated in the bill for a time to dispatch it. Fish that have spines they can erect are thoroughly handled, so they are dead before they make the long journey down the esophagus. In some especially spiny prey species, the herons actually manage to break off the spines before they swallow the fish.

Although usually feeding in the water or at the waterside, the herons’ diet is not confined to fish. They feed on just about anything they can catch in the water, including frogs, salamanders, garter snakes, crayfish, and even large insects. They also spend much time foraging on land, especially in winter when surface fishes tend to go deeper. In the Pacific Northwest, voles are an important part of the diet, and it is commonplace to see the herons hunting in meadows and farmlands.

Foraging by herons is usually solitary, and they are quite territorial at that time, with long, sometimes noisy, chases when one gets too close to another. They also fly by themselves, but at high tides, sometimes several birds roost in the same tree or on the same sand bank, near one another. This heron is an adult, with characteristic black head plumes. Herons fly with their neck folded back. Their wings are very large, about the size of eagles that are many times their weight, and they allow the heron to fly very slowly and land in shallow water with scarcely a splash.

The other bird shown here is a true crane of the family Gruidae, quite unrelated to the herons. This Sandhill Crane (Grus canadensis) is only very rarely encountered near Puget Sound, although large numbers migrate through eastern Washington and many birds winter in the southwest corner of the state, especially in the Vancouver to Woodland area, where they can easily be seen in open fields and marshes.

Sandhill Cranes are gray, often tinged with brown, and have red naked skin on top of their head. Their long tertials (innermost flight feathers) hang over their rump and tail, giving them a quite different shape from that of a heron.

Cranes forage by walking slowly through their habitat, often a partially flooded meadow, with head forward. They watch for prey in front of them, which they grab suddenly and then swallow it. Although they eat some of the same things that herons do, for example small mammals, reptiles, and amphibians, they take very few fish and many more insects, as they forage mostly on land. Herons eat no plants, but plants feature prominently in the diet of cranes, especially grains, berries, and the tubers of aquatic plants. As they do for geese and ducks, federal and state wildlife agencies manage refuges for cranes by planting grains.

Unlike the herons, cranes are often seen in flocks, sometimes large ones. They spread out somewhat to feed but return to their flocks to roost and to fly about the countryside. In flight, their wing beats are rapid and their neck is held out straight. A distant flock might be mistaken for a flock of geese, flying in a line or vee formation.

Dennis Paulson

RUDDY DUCKS ARE ODD DUCKS

2010-11-16T10:01:00.000-08:00

Most ducks of the North Temperate Zone mate in the winter, then the pair flies to their breeding grounds, where the female builds a nest and lays eggs. When she begins to incubate the eggs, the male deserts her, and there is no pair bond until the next fall, when the cycle begins again.

Ruddy Ducks (Oxyura jamaicensis) are quite different, and this might have been predicted, as they are the only northern ducks in which males molt in the spring into a bright breeding plumage, much as many shorebirds and passerines do. This is the rich red color that gives the species its name. The male bill, gray during winter, turns intense sky blue from structural changes.

There is no courtship or mating on the wintering grounds, but as soon as the birds arrive on their breeding grounds in spring, intense mating activity takes place. The males display actively at each other and at nearby females. The display consists of the male bumping its bill on its chest rapidly, creating bubbles in the water around it. This Bubbling Display is usually followed by a rush across the water in Display Flight, looking and sounding like a little motor boat. The loud noise accompanying the latter is made by the feet.

Male Ruddy Ducks are fiercely aggressive to one another and to other waterfowl when in mating mode. Females also can be very aggressive. Grebes and coots are not happy sharing ponds with Ruddy Ducks, and vice versa. They are not territorial, but the male stays very close to the female with which he is mated, even if only temporarily. Many males form a monogamous pair bond with a single female, some form pair bonds with a second and rarely a third female, and some appear to form no pair bonds at all, merely attempting to mate with any receptive female.

Now, about duck breeding. Most birds copulate by the male and female pressing the opening of their cloacas together, during which time sperm is transferred. But some male birds, including ducks, have a copulatory organ, the penis. This organ is not homologous to the mammalian or reptilian penis but is an erectile extension of the cloacal opening, as if a glove were turned inside out.

Ducks mate in the water, and cloacal appression might not be adequate for effective sperm transfer in the aquatic medium, so the evolution of a copulatory organ would have been an appropriate adaptation. The unequal sex ratio in ducks, with intense male competition for females, might also play a part in this adaptation. The penis is corkscrew-shaped, and the female vagina is similarly shaped in the opposite direction, so most mating attempts, especially between unmated birds in which the female does not cooperate, may be unsuccessful.

The Lake Duck (Oxyura vittata) of South America apparently has the longest penis in relation to its size of any vertebrate. It may be up to 40 cm, as long as the body. This species is closely related to the Ruddy Duck, which – as far as the present record books show – can develop a penis only about 25 cm long. A very interesting recent finding is that in a given wetland, only certain males develop the longest organs, and these are dominant to the others and the most successful breeders.

There is plenty more of interest about this odd duck. Ruddy Ducks lay the largest eggs with respect to body size of any duck, the average clutch of 7 eggs weighing about as much as the female herself. Thus the young hatch in a very precocial stage, grow quickly, and are abandoned by the female when about three weeks old, before they can fly. Speaking of flying, Ruddies are the poorest fliers among the ducks, rarely seen performing this activity. They apparently move around between wetlands and migrate entirely at night.

They are very highly adapted divers, with big feet that propel them under water, a compact body, and a long tail that may provide steering. They seem to be specialists on midge larvae, which make up the majority of their diet wherever studied. Because their prey is abundant and often evenly distributed, Ruddies can aggregate in large flocks that can find enough to eat even though there are many of them. They feed by diving to the bottom and slurping through the mud to strain out the larvae. They can feed actively for a while, fill up with midges, and then sleep, so our encouters are often with sleeping flocks.

Dennis Paulson

DUCK MATING GOES ON AND ON AND ON

2010-11-11T14:09:00.000-08:00

It’s nowhere near spring, but believe it or not, there are many Pacific Northwest birds in the throes of intense mating behavior. Those birds are ducks. Ducks have a peculiar mating system, unique among birds. They form a strong pair bond, but it is mostly during the nonbreeding season!

Males of most temperate-zone ducks have bright, species-specific plumages, quite different from the drab plumages of females, many of which look very similar to one another. But these bright feathers are displayed from fall to early summer, and they are replaced during midsummer by a dull, female-like basic plumage (often called “eclipse” plumage). Displaying “breeding” plumage in fall, winter and spring and “nonbreeding” plumage in summer seems quite reversed from the situation in other birds, and in fact it is.

Most temperate-zone ducks are migratory, moving from breeding grounds in marshy freshwater wetlands to larger ponds and lakes and the ocean itself after breeding. Some duck species arrive on their wintering grounds while still in basic plumage, and the males molt fairly quickly into their beautiful alternate plumage. Other species, later migrants, molt farther north and arrive already in full color.

Almost as soon as the flocks arrive on their wintering grounds, the urge to mate kicks in, and the males begin to court the females. Those that arrive early wait until they have molted, but those that arrive late can begin the process immediately. Male ducks all have distinctive displays, which, coupled with their bright, species-specific colors, produce a dazzling show. Behavior involved in mating, both aggression and courtship display, is at its best in groups, with multiple individuals of both sexes.

Most male dabbling ducks have bright, contrasting markings around the head and breast and additional bright markings around their rear end. As soon as you see them display, you realize these color patterns are incorporated into the display. The displays are quite stereotyped, male Mallards, for example incorporating distinct display behaviors called Grunt-Whistle, Head-Up-Tail-Up, and Down-Up. Distinct behaviors are usually capitalized when written about in scientific literature.

Female Mallards perform head movements, bill-jabbing behavior, and characteristic vocalizations to indicate interest in copulating with a particular male. Females of most species will show aggression to males other than their mates. Copulation between pairs starts in the fall and continues through the winter into spring, when the birds return to their breeding grounds. Maintaining the pair bond seems to be the important function of this activity, which of course does not result in eggs being formed.

Displays in goldeneyes and mergansers are among the fanciest. In male goldeneyes, the head is thrown back almost onto the back, with a big splash when the feet kick back and an accompanying throaty note. In Red-breasted Mergansers, the male ends its display with tail down, back up, breast sinking into the water and neck extended upward with open beak, the whole thing reminiscent of some reptilian ancestor.

Some ducks rush along the water or fly short distances in their courtship. Buffleheads bob their heads violently up and down, fly just over the female and land by skiing on their bright pink feet, and cock both wings forward, exposing their big white patches. As part of their display, male Black Scoters also rush along the surface but with head down. A male Surf Scoter flies for 20-30 feet, wings whistling loudly, then drops feet-first into the water with wings raised. These display components are stereotyped in form and the order in which they are presented.

Because there is heavier predation on females when they are nesting, there are more male than female ducks in winter. Thus by spring there are still many unmated males. Courtship becomes even more intense, as gangs of male ducks roam around trying to find unmated females and spending much time harassing pairs to try to separate them (usually unsuccessfully). A lone female may be harassed by numerous males, and forced copulations are common at that time.

Finally, it’s time to make something of all that time spent mating. The pair heads off to wherever it is they breed, still maintaining that bond. They arrive, and the male has a fresh bunch of rivals to deter. The female quickly constructs a nest and lays her clutch of eggs, all the while shadowed by her mate. As soon as she begins to incubate, he leaves the scene and begins to hang out with other males in the same state. They typically move out into deeper water, begin their molt into basic plumage, and drop their flight feathers in preparation for growing a new set. It’s a new year in the odd annual cycle of a male duck.

Dennis Paulson

THE SNOW GEESE HAVE RETURNED

2010-10-28T13:24:00.000-07:00

Here it is late October, and the Snow Geese (Chen caerulescens) have made their annual transhemispheric trip from Wrangel Island, off the north coast of Siberia, across the Bering Straits and down into North America. Up to 100,000 or more birds are thought to make this journey, without a doubt the largest crowd of emissaries from Russia to the United States. Forty thousand pairs are thought to breed on Wrangel Island, and they bring with them the young produced each year.

Half of these birds remain for the winter in the Fraser River and Skagit River valleys of southwestern British Columbia and northwestern Washington, the other half continuing down to major wintering grounds in southern Oregon and California’s Central Valley. Many of the birds have been banded on Wrangel Island, and they bear conspicuous numbered plastic neck collars.

This migration, of very large numbers of birds moving from restricted nesting grounds to restricted wintering grounds, is typical of geese, which seem to function best in a highly social setting. They are herbivores, grazing on grasses and forbs in open areas, and there is usually more than enough food for all. If you’re a herbivore, the world is your breakfast (lunch, dinner) table! Especially if you can eat just about any kind of herbaceous green plant.

These large groups of geese probably facilitate mating (the young birds are surrounded by potential mates) and predator awareness (how could a potential predator sneak up on such a large number of eyes and ears?). The major predator of the Skagit Valley geese is the Bald Eagle, but predation is infrequent. Eagles probably get mostly sick and infirm birds, the ones that don’t make it into the air when an eagle flies over and flushes an entire flock (which may include thousands of birds).

On the nesting grounds on Wrangel Island, Arctic Foxes take their toll. But the greatest mortality source of our Snow Geese may be from hunting on their winter grounds. Birds wounded but not killed by shot probably fall victim to eagles and possibly other predators such as Coyotes. Nevertheless, hunting is strictly regulated and has negligible effect on the goose populations.

The average clutch of Snow Geese is about four eggs. Of them, 80% reach hatchling stage, and 75% of those reach fledging. Thus each pair of adults should produce on average about two young each year. Without heavy mortality, this would lead to a population increase, and that in fact is what is happening with Snow Geese throughout most of their range, leading to conservation and management problems. The widespread availability of agricultural land in winter and the opportunity to expand to new nesting areas in the Arctic combine to enhance population growth. The Wrangel Island population is an exception, having been stable in recent years.

Many immatures are evident in the Skagit flocks, in their distinctive gray plumage. The immatures attain adultlike plumage by the time they are one year old but do not breed until they are three years of age. The birds are censused annually, and the percentage of immatures in the wintering population is an easy way to measure breeding success in the previous summer. Young birds of this population pair during their third winter, and the pair stays together until one of them dies; life span may be two decades or more.

The Snow Geese of the Skagit Valley provide one of the most spectacular of wildlife spectacles in the state. Throughout each winter, carloads of people stop in designated parking areas and watch flocks, sometimes immense flocks, of the geese feeding and flying at pointblank range. They are surely the envy of groups of hunters waiting in vain in nearby fields with their “flocks” of decoys. The birds move between feeding areas, so there are often birds in the sky coming and going.

To see a V-formation of Snow Geese approach from high in the sky, then drop toward the ground by dumping air from under the wings, some of them even briefly upside-down, furnishes a thrill for all who are watching. At the last moment of their descent, the birds extend their webbed feet and spread their tail, as if putting on the brakes, flap vigorously, and settle to the ground. Heads down, they move slowly forward, biting off grass blades as they go. Grass is planted in wildlife management areas set aside for the geese.

These flocks should be checked for the so-called blue morph, previously thought to be a different species, the “Blue Goose.” This morph is common in the central Canadian breeding populations that winter in central United States but has always been rare in the Pacific Northwest. Apparently a few such birds have found their way into the Wrangel Island population, and we see them every winter. They are easily recognized by their dark body and white head; the immatures are much darker than typical Snow Geese.

Dennis Paulson

BIRD FEEDING – SHOULD WE DO IT?

2010-10-21T09:17:00.000-07:00

In North America, more people feed birds than ever before. The number of bird feeders is surely in the millions all across the continent. In some urban and suburban neighborhoods, it seems as if most yards have a feeder or two. However, any quick survey will show that some of them have not been recently replenished. Bird feeding has its aficionados, but not all of them are passionate about it.

So many people feed birds that a cottage industry of feeders and food types has sprung up. A trip to the nearest Wild Birds Unlimited store will make that clear. Seed feeders are among the most common, with a wide variety of seeds, especially millet and sunflower seeds. Look at the ingredients of a bag of some of the fancier seed mixes sometime to see the breadth.

Suet is another ingredient in the cuisine served in many a yard. This fat-based item has always been especially favored by birds during the low temperatures of winter, but there are now many “no-melt” types that provide food during the heat of summer as well. You can get suet now with just about anything in it, from raisins to insect parts. Suet diversity follows the evolutionary pathway common to all of our consumer items, although it’s not clear how much difference all these additives make to the birds.

Presumably most people who feed birds are sympathetic to animals and nature, and surely the majority are environmentalists. But as such, shouldn’t we be thinking about what effects we are having on the birds and the environment? What are the pros and cons of bird feeding?

It strikes me that there are really two positive aspects of bird feeding. First, we are supporting bird populations (or at least individual birds). This is probably not very important during the summer or at any time when there is plenty of natural food available. Most birds live in places that furnish sufficient food and adjust their migratory behavior to the availability of food.

But there is always the possibility of unusually hard times, when weather phenomena make food suddenly more difficult to obtain. The most obvious example of this would be a heavy snow storm, blanketing the ground and all the potential food on and in it. Think of a finch eating weed seeds or a jay digging up cached acorns. Suddenly, these resources would be unavailable, and the presence of a dependable bird feeder could make all the difference between life and death. This could be called “bird benefit.”

The other important positive aspect of bird feeding is human benefit, to bring the birds closer to us in greater numbers. Birds that come to a feeder daily are in far greater density and variety than we would see just by randomly looking out the windows of our homes. This must be a prime motivator for many people who feed birds. Of course, our gaining a better love of and understanding for birds in this way probably benefits the birds as well.

Are there negative aspects of bird feeding? The seeds that spill from feeders are avidly eaten by rats at night; some of them are out in broad daylight! For those who don’t like rats much, this is a consideration, although they are usually out of sight and mostly out of mind. Many people also consider Eastern Gray Squirrels unwelcome pests at feeders, as indicated by the great variety of “squirrel baffles” on the market.

More seriously, bird feeding does affect the birds. Feeders attract birds near houses, and occasionally a bird will be startled from a feeder and fly into a window with fatal consequences. Of course, many birds strike windows even without feeders.

Our feeders also may attract predators, from bird-eating hawks to cats, and by concentrating the prey at a feeding location, the predators may have an easier time capturing them. This is surely the case for cats. Some have even called these locations “cat feeders.” In addition, parasites and diseases are surely more easily spread when birds gather at abnormal concentrations of their food. Seed-eating siskins and grosbeaks may contract salmonella and even die at feeders during outbreaks of that disease.

Hummingbird feeders are particularly widespread; hummingbirds seem to find them readily no matter where they appear. These feeders have been responsible for dramatic changes in the winter range of some North American hummingbirds, and their presence has allowed Anna’s Hummingbirds to greatly expand their breeding range in all directions, including far to the north.

As a resident species, the Anna’s have to take the consequences of a hard freeze and a feeder-owner without the motivation or opportunity to keep the feeder thawed. Perhaps there are so many feeders that there is usually an alternate one not very far away. One consequence that has not been examined is the loss of pollination by flowers that were formerly visited by migratory hummingbirds!

Bird feeding has even become part of the tourist industry. Numerous sites in the New World tropics feature clusters of hummingbird feeders that attract hundreds of individuals of up to a dozen species of hummingbirds, providing education as well as recreation for nature-minded tourists.

In any case, there is no concrete evidence that feeding birds is either totally good or totally bad for them, so we can use our own judgment to decide. We might not put food out because we are concerned that a bird might fly into one of our windows because of the feeders. Or we might put food out just to enjoy their presence, perhaps even helping them survive a cold snap.

Dennis Paulson

DIFFERENT MOLT STRATEGIES

2010-09-07T11:35:00.000-07:00

Most birds molt their flight feathers in a fairly straightforward way, as explained in the last blog. The feathers on each wing molt sequentially, starting with the innermost primary and usually ending with the innermost secondary. This is called sequential wing molt.

But there are two other ways to do it.

Very large birds (above about 1 kilogram in weight) that need to be able to fly at all times, for example eagles, cormorants, and herons, can retain feathers for more than one year and molt only some of them each year. The largest among these take about three years to replace all the flight feathers. This molt strategy is called stepwise wing molt.

In many large birds, you can see the different feather generations in an outspread wing because the older feathers are more worn and thus a bit paler. These differences should be evident in this Turkey Vulture wing specimen from the Slater Museum collection.

The other strategy is simultaneous wing molt. If predation is the only reason they need to be able to fly, and birds can avoid predation, they can give up flight for a period of time and drop all their flight feathers simultaneously. This is the case in anhingas, ducks and geese, loons, grebes, and larger alcids, all of which can remain in the water during this period, out of range of their potential predators. Note this group includes the very large swans and geese, which perhaps could not fly very efficiently with gaps in their wings.

The female Mallard is typical of midsummer ducks with all flight feathers missing. The Common Murre also is in full wing molt, usually obvious because the wingtips can’t be seen above the tail.

This Anhinga has dropped all of its flight feathers and most of its tail feathers simultaneously and is in the process of growing them back.

Dennis Paulson

IT'S TIME TO MOLT

2010-09-07T11:21:00.000-07:00

All birds have a complex coat of feathers, thousands of them, which they use for insulation, display, camouflage, and flight. Look at a feather closely and you’ll see that it looks flimsy, yet it does its job very well by meshing with others of its kind. Flight feathers can hold up birds such as Trumpeter Swans that weigh in excess of 30 pounds and provide thrust and lift for continuous flight in birds on migrations that extend thousands of miles.

But these feathers, while strong, are not indestructible. Inexorably, a feather wears over its lifetime, and if a bird grew only one coat of them, eventually wear would take its toll. If not naked, a bird would look rather frazzled. Over time the feathers would lose their strength and insulating ability as the microscopic structures that hold them together wore off. Look at the same feather when about a year old, and you can easily see that wear. This Little Gull wing in the Slater Museum collection, from a one-year-old bird just molting into its second set of wing feathers, shows you how worn feathers can become before they are replaced.

The solution to this problem is the annual molt that all birds undergo. All the feathers on the body are replaced each year, usually soon after breeding, which would be in fall in our north temperate zone. Not only are the contour feathers of the body replaced, but all wing and tail feathers are replaced as well, except in the very large birds in which this isn’t energetically possible (see next blog post).

It takes a lot of physiological energy to grow a feather, so molting is a fairly slow process. A complete body molt takes as long as a month for an average songbird. Individual flight feathers take about three weeks to replace completely, so a complete wing molt may take a month or more. These constraints are very important to migratory birds, as they may not be able to migrate until they have finished growing all their flight feathers, and they molt only after breeding, with its own energetic demands, has been completed.

Wing molt is typically sequential. The innermost primary is shed, and its replacement begins to grow. Before it completes its growth, the second primary is shed and its replacement begins to grow. Etc. The molt progresses out the primaries and, at some point, begins in the secondaries, where it moves from the outermost (adjacent to the primaries) inward. This gull is in the middle of primary molt, with the two outermost feathers from the previous generation and the feather just in from those growing in. You can also see that some of the outermost secondaries have been shed.

This adult Black Turnstone shows body molt (worn brownish feathers being replaced by crisp blackish ones) and wing molt (worn brown primaries and newly grown blackish ones, with a gap where the intervening feathers have been shed and are regrowing). Most birds would look something like this in fall.

Of course, in birds that change plumage color between breeding and nonbreeding times, molt of the body feathers must occur twice each year, spring and fall. This molt is one of the most obvious ones to those of us who look carefully at birds. This juvenile Short-billed Dowitcher is just beginning its molt into its dull first-winter (much like adult) plumage; the scapular feathers are often the first to molt.

Dennis Paulson

A CROW FAMILY

2010-07-27T14:13:00.000-07:00

It’s not easy to get to observe the development of young birds in a nest, Most songbird nests are hidden away, hawk and eagle nests are high in trees, woodpeckers nest in holes, and ground-nesting birds tend to be precocial, the young leaving the nest soon after the eggs hatch. So when an opportunity presents itself, it’s worth taking advantage of it.

This nest of crows (American Crow, Corvus brachyrhynchos, or Northwestern Crow, Corvus caurinus) was discovered on the seventh floor of a building in the University of Washington Medical School in Seattle. The person whose office was above it alerted Netta Smith to the opportunity, and she brought a camera to work with her many days over the ensuing month to document the development of the crowlets. I was able to drop by on one occasion and watch the action when the birds were about to fledge.

Unfortunately, the eggs had already hatched when the nest was discovered. The average time until young crows leave their nest is about 32 days in the Pacific Northwest, so the eggs probably hatched on about May 1. Thus at the time of the first photo on May 5, they were about four days old. As the month progressed, the young birds looked more and more like crows.

The young developed rapidly with a constant input of food brought by the two parents, which must have had a busy time finding enough for them. Food items seemed to be mostly small and were difficult to identify, but at least some insect larvae were noted. Human garbage likely played a part, as crows in the city forage constantly in dumpsters, but they surely captured “natural” prey as well. No bird eggs or young were seen, but they play a significant part in the diet of crows.

One young disappeared from the nest and was subsequently seen on a ledge several floors below, presumably killed by a fall. This is surely more of a hazard in such a nesting place; tree branches might have stopped its fall. The other four young flourished until, one by one, they left the nest. They tussled with one another as they got larger, and when about ready to fledge, exercised their wings again and again. Netta did not see any of them actually leave the nest, but on one occasion one spent the day on a ledge across the courtyard and was fed again and again. Then they were gone.

One of the most notable things about young crows is their blue eyes. Young corvids often show signs of immaturity by having eye or bill color different from that of the adults.

Dennis Paulson

A BUSY RED SQUIRREL

2010-07-13T16:37:00.000-07:00

On July 5, I spent some time watching a Red Squirrel (Tamiasciurus hudsonicus) processing Sitka Spruce (Picea sitchensis) cones at Manning Provincial Park, British Columbia. These small squirrels (around 250 g) are frenetically active and noisy, and watching them is much like watching birds go about their activities.

Two things impressed me about this behavior, persistence and proficiency. The forest floor, in a big grove of spruces, was literally covered with cones. Obviously it was a great cone year, not always the case in any given stand of conifers, and the squirrels were taking advantage of it. This particular squirrel would take only a few seconds to locate a cone on the ground, grab it in its mouth, and carry it up to one of its favored perches on a big fallen spruce trunk.

Fortunately, this was at eye level for me, right out in the open and allowing for continued photography. I don’t know why, but he (it was an obvious male) kept coming back to the exact spot to open the cones. And he did it again and again and again. That was the persistence part. But there is every reason for them to be persistent. When food is abundant, go for it.

Proficiency was also obvious. Each cone was held only for a few minutes, while the squirrel bit off each cone scale and swallowed the seed beneath it. I couldn’t determine whether the seeds were chewed or merely swallowed, as the process was so rapid. Sitka spruce seeds are relatively small (3 mm) conifer seeds, so perhaps they could be swallowed without chewing. However, they also have a “wing” that facilitates their dispersal by wind, so that must presumably be discarded.

In any case, each cone was reduced to its central axis in just a few minutes of manipulating it, the scales falling like confetti in front of the squirrel. It was then dropped, and invariably the squirrel gave its territorial chattering call for a few seconds. then it would hop off the log and pick up another cone and start again.

This squirrel processed cone after cone as I watched. Although Tamiasciurus squirrels are well known to store many of the seeds they harvest to feed on them over the winter, I saw no indication of any caching behavior. Red Squirrels cache bushels of green spruce cones in a single protected spot throughout the summer, and these cones become important when the ground is made inaccessible by deep snow.

When cached by certain verterbrates, some seeds that are stored are lost or forgotten, and they have the potential to sprout into new plants. In some cases (gray squirrels with oaks, nutcrackers with pines), the animal may be as important in the dispersal and reproduction of the plant as the plant is in the diet of the animal. This is not the case with Red Squirrels, which, because they store cones before they open, function entirely as seed predators and not as seed dispersers.

Closer to the coast of the Pacific Northwest, including all of Puget Sound country, it is the Douglas Squirrel (T. douglasii) that typically feeds on Sitka Spruce seeds. It is just as persistent and proficient.

Dennis Paulson

POORWILL, BEAUTIFUL BIRD OF THE NIGHT

2010-06-22T08:56:00.000-07:00

Common Poorwills (Phalaenoptilus nuttallii) are widely distributed throughout western North America, but how many of you have seen one? They are strictly nocturnal and perfectly camouflaged in their daytime resting sites.

On a recent early June trip to eastern Washington, we drove up Robinson Canyon, west of Ellensburg, in the evening. Robinson Canyon is a riparian oasis in the midst of sagebrush shrub-steppe and ponderosa pine woodland. We arrived at about 8 pm at a gate in the fence that encloses part of the L. T. Murray Wildlife Recreation Area. As it got darker and darker, we enjoyed the sights and sounds of the local songbirds going to bed. A Western Wood-Pewee sallied after insects later than we expected a flycatcher to be out and about. Another one sang its dusk song nearby.

But we were after more elusive game. As it got dark, our quarry began to stir. At 9:12 pm, a poorwill called its name from the nearby shrubby and rocky hillside. Several others followed in succession, until a steady chorus of melodious ‘poorwill . . . . . . poorwill . . . . . . poorwill’ resounded from the hillsides. At 9:27 pm, we saw the silhouette of a bird flitting across the road. We started the car and pulled away from the roadside at 9:30, when it was entirely dark.

Very soon the headlights picked up a poorwill resting on the road. This bird eats large moths and beetles that it sees against the sky as it rests on open ground, and roads through its habitat often represent the most open terrain for a foraging bird, so we were taking advantage of this long-known way to get a look at poorwills. Their eyes shine brilliant orange in the light of the headlights.

Seven poorwills flushed from the road in the three miles of road we drove, and fortunately, as the goal of the evening was to get photos, two of them remained on the edge as we slowly drove by them, allowing shutters to click to complete satisfaction. The huge eyes, tiny beak (but the gape extends back behind the eyes), and tiny feet (almost useless for locomotion) were visible at close range.

Trying to find them in the daytime is another story. They sometimes perch right out in the open, on broken ground or rocks, but seeing one before you flush it is an art or science that is beyond me. I once chased one around, trying to get photos of it in broad daylight, and I could never see it before I flushed it, sometimes within a few meters. Their camouflage, I thus conclude, is perfect. Joe Marshall, an ornithologist who spent a lifetime studying nocturnal birds, called the Common Poorwill the most beautiful bird.

But poorwills are much more interesting than just being big-eyed, big-mouthed nocturnal insectivores. They were the first bird to be discovered “hibernating,” in deep torpor in a south-facing rock crevice in southern Arizona. Amazingly, this species is still the only bird known to spend long periods in torpor, remaining completely inactive for days during periods of low temperatures during winter. At those times, body temperature can drop to 5°C, oxygen consumption to <10% of normal. This has the earmarks of true hibernation, but it is not. Instead, it is a day-to-day phenomenon, not the deep winter sleep of marmots and other mammals. Poorwills may enter this state at any time of low temperatures, an energy-saving strategy that allows them to cope with periods when no insects are out and about.

Dennis Paulson

BLACK SWIFT, BIRD OF MYSTERY

2010-06-22T08:48:00.000-07:00

The Black Swift (Cypseloides niger) is one of the more poorly known North American birds. Seen by most people in flight high overhead, its comings and goings are only poorly documented.

Swifts are aerial insectivores. Their very long wings, with extremely high aspect ratio (length/width), allow them to glide effortlessly or move forward at high speed by rapid wingbeats. They are large enough that their wingbeats are more obvious than those in smaller swifts such as Vaux’s. Not only can they fly for long periods while foraging, but they can fly long distances as well, This serves them not only for long-distance migration (they winter in northern South America) but also for daily foraging trips.

The diet of these birds is of course made up of flying insects. The prey is usually about a centimeter in length or less and may be flying ants, wasps, flies, beetles, leafhoppers or anything else that they can find in the air. Foraging is often very high, beyond the limits of human vision, but during cloudy and cool weather, the birds come much lower, often feeding over water bodies, where insects are usually present even in bad weather.

Because they are such superb fliers, the swifts can wander 80 km or more from their montane nesting areas in a single flight to look for food. They stay away for many hours, accumulating insect prey in a sticky mass in the throat. When they return to the nest, they feed the young by regurgitating this mass a bit at a time.

Nesting is always on cliffs, either on rugged coasts or in mountainous areas, usually behind a waterfall. The nests are built of moss (or moss and seaweeds for coastal nests). Because foraging is an uncertain business if you’re a swift, creating quite a challenge when feeding young, this species lays only one egg. Food delivery must be spotty, even with two parents providing it, as the young takes about seven weeks to leave the nest. Compare that with a nestful of five baby robins that fledge in two weeks!

While censusing birds at Port Susan Bay, Snohomish County, Washington ornithologist Steve Mlodinow observed numbers of these swifts at close enough range to get magnificent photos, perhaps the best ever taken in flight. These photos generated a lengthy discussion about why some birds had white tips to the feathers of their underparts and others didn’t. The consensus, aided by examination of specimens in the Slater Museum, is that the white-scalloped birds are females. In addition, the spotted birds had shorter tails. Sexual dimorphism is quite unusual in swifts, and its significance in Black Swifts is unknown.

Much is to be learned about this species, perhaps not easily. For example, no one has seen Black Swifts copulate; there is a challenge for an adventuresome field observer!

Dennis Paulson

FLORAL EXPLOSION

2010-04-27T09:20:00.000-07:00

Spring is a wonderful time of year for the Northwest naturalist. Everything seems to be happening at once. Migrating birds arrive every day. Butterflies add their erratic movement to the landscape. And flowers are everywhere.

The most spectacular flower shows in spring are in the open country and pinelands east of the Cascade Crest. They easily equal the floral spectacle that makes a midsummer mountain hike such a delight, although they are surely less appreciated. But they are worthy of the effort it takes for a Puget Sounder to plan a trip east. Starting as early as March in the sagebrush country, the spring flower show slowly moves uphill with the increasing temperatures of spring and reaches its peak in early May in the grasslands at the lower edge of the Cascades.

Sagebrush buttercups (Ranunculus glaberrimus) and yellow bells (Fritillaria pudica) start off the parade of colors with bright yellow spots in the gray sagebrush landscape. They’re followed by the more conspicuous show of big balsamroot (Balsamorhiza deltoidea) bouquets and wide washes of white and purple phlox (Phlox spp.). Just these flowers alone create a macro-spectacle in that part of Washington, easily viewed from the main highways.

But to see all the phytodiversity you can imagine, get off the highways. Back roads near Thorp or the Umtanum Road southwest of Ellensburg provide as good a flower show as anyone could desire. Drive slowly or walk out through the habitat. Check out open rocky areas for spectacular pink bitterroot (Lewisia rediviva) and Simpson’s hedgehog cactus (Pediocactus simpsonii) flowers and look for the beautiful color scheme of sagebrush violets (Viola trinervata).

And come back about every two weeks to see the turnover, as species after species blooms. You can only hope that there are enough pollinating insects out there to see to the needs of all these sex-starved flowers.

Dennis Paulson

SHOREBIRDS ON THE MOVE

2010-04-20T09:23:00.000-07:00

Every spring, about the beginning of April, flocks of shorebirds begin their annual migration up the Pacific coast on their way to Alaska and other points north. Sandpipers and plovers by the tens of thousands use the coastline as a pathway to their summer homes, feeding on the abundant populations of marine invertebrates and depositing fat to fuel their long-distance flights to their breeding grounds. Some birds leave the Washington coast and fly directly across the Gulf of Alaska to southern Alaska, where they stop at estuaries such as the Copper River Delta.

The most common species are Western Sandpipers, Dunlins, and Short-billed Dowitchers, in that order. At the same beaches, mudflats, and tidal pools are smaller but still substantial numbers of Black-bellied and Semipalmated Plovers, Greater Yellowlegs, Whimbrels, Marbled Godwits, Ruddy Turnstones, Red Knots, Sanderlings, Least Sandpipers, and Long-billed Dowitchers. At the same time, Black Turnstones, Surfbirds, and Wandering Tattlers feed along rocky shores as they move north, and Red-necked and Red Phalarope flocks settle on the ocean offshore.

These birds take advantage of a spring flush of invertebrate growth and recruitment, and they find no lack of goodies to help them put on weight. Amphipod crustaceans, polychaete worms, and small bivalves are among the most abundant fauna in birds that feed on and in sand and mud. These animals are so abundant that just about all the shorebird species using the area feed on them. Barnacles, mussels, and snails are staples of the rock shorebirds, and planktonic crustaceans fill the bellies of phalaropes.

Shorebird migration peaks on the Washington coast in the last week of April and first week of May, when the maximum number of species and individuals are present. Grays Harbor and Willapa Bay and the beaches adjacent to them always support the largest numbers, and the abundance of these birds provides a stirring spectacle every spring. Concentrations of some species in Grays Harbor are the highest south of Alaska.

And there is a Grays Harbor Shorebird Festival every spring to enjoy these concentrations: http://www.shorebirdfestival.com/.

Unfortunately, shorebird numbers have been declining, so the spectacle gets a little less spectacular every year. More importantly, we don’t have a good handle on the cause of the decline. Presumably it relates to loss of habitat on either the wintering grounds or at migration stopovers, as the arctic and subarctic breeding habitats are still relatively intact.

It’s also possible that anthropogenic changes are reducing the abundance of shorebird prey, another factor that we don’t know much about on a grand scale. There are still lots of shorebirds, so we have some time to work out an effective conservation plan, and there is such a plan for the U.S. (http://www.fws.gov/shorebirdplan/).

Dennis Paulson

AMPHIBIAN DEFENSES

2010-03-22T09:46:00.000-07:00

One reason that amphibians in general are in trouble (well, with the exception of Bullfrogs and Cane Toads) is that they have very porous skin, so they are more likely to pick up environmental contaminants than are other vertebrates. The chytrid fungus that is killing so many of them attacks their skin, perhaps interfering with dermal respiration or water balance.

Thin-skinned and small, it would seem that amphibians would be almost defenseless against the whole array of predators with which they share their world. But they’re not!

In part because of their sensitivity to drying out, most amphibians are nocturnal. But this also is a first line of defense against diurnal predators, among which birds are by far the most important. There are many hawks that relish amphibians, and in the tropics members of many different bird groups eat frogs. Of course, by being nocturnal, the frogs are subject to owl predation; you can’t win them all!

Many species, even though active at night, spend the day at least partially exposed, and they are usually very well camouflaged, green for the leaf-sitting frogs and brown for those on the forest floor.

Frogs are also escape artists. The great leap forward that a frog can take with its long legs allows it to capture prey very effectively, but the leap is probably even more important for predator avoidance. A Wood Frog (Rana sylvatica) at the edge of a pond heads for the water at the least disturbance, arcing through the air on the way there. Plunging into the water, it immediately makes for the bottom sediments, where it disappears.

Nocturnal life style, camouflage colors, and escape locomotion notwithstanding, amphibians are still captured. For many species, the next line of defense is provided by their skin toxins. Many of them secrete chemicals in the skin that are poisonous to other vertebrates. Sometimes these are concentrated in particular glands, often around the head (predators often grab their prey by the head to dispatch it most quickly). Note the big toxin-secreting parotid glands behind the eyes, presented to the potential predator by this Northwestern Salamander (Ambystoma gracile).

Many of these amphibians are nocturnal and cryptically colored. But others are either active in the daytime or can be found where they spend the day only partially hidden. Toad tadpoles are toxic, and instead of scattering out and hiding as do the tads of other frogs, they congregate into big, black, wiggly masses, and a predator that captures one and then spits out the bitter-tasting morsel can easily learn to avoid such groups.

These include many species of poisonous frogs, for example the Strawberry Poison-dart Frog (Dendrobates pumilio). Many of these species are conspicuously, even garishly, colored. This is warning coloration (also called aposematic coloration), and predators that learn not to bother with this prey presumably leave more descendants.

Rough-skinned Newts (Taricha granulosa) of the Pacific Northwest are cryptic brown when viewed from above, but when disturbed, they display their bright orange undersurface as a warning coloration. These newts are extremely poisonous and have killed people who swallowed them (just on a dare, can you believe it?). The tetrodotoxins in their skin are poisonous to just about anything that tries to eat them and in fact are among the deadliest poisons known to have evolved.

But some populations of Common Garter Snakes (Thamnophis sirtalis) have evolved resistance to this toxin and can eat the newts with no ill effects! This “evolutionary arms race” has been won by the snakes in this case, but not in all populations.

Dennis Paulson

FROGS ARE JUMPING!

2010-03-22T09:14:00.000-07:00

Spring in the Pacific Northwest was made for amphibians. They flourish in cooler temperatures than reptiles, and they do best where it’s wet, so the cool, wet springs of this region are great for them. And because amphibians need moisture and are small and have many predators, most of them are active at night, so that’s the time to be out looking for them. Most amphibian hunters use a headlamp to keep their hands free, as amphibians are elusive little critters.

There is a moderate diversity of frogs in this area, some of them common. The most ubiquitous is the Pacific Chorus Frog (Pseudacris regilla), and it seems as if they can hardly wait to start breeding. Individuals are heard calling during warmer winter days, and the choruses really start up by February. Their ribbit call is known to all because so many movies are made in Hollywood, where the species is common. The call is first heard individually and then swells into a chorus, as more and more males head for the wetlands in which they breed.

The Western Toad (Anaxyrus boreas [formerly Bufo boreas]) was also one of the most commonly seen frogs in the Northwest, but this is one of the species that has declined greatly in recent years, as part of the Great Amphibian Problem. We don’t see as many of them as we used to, but they are still widespread. If you can’t find an adult, you may see masses of little black tadpoles swimming together in a mountain lake or a shore lined with toadlets that have just undergone metamorphosis in late summer.

The Red-legged Frog (Rana aurora) is the common native frog that looks like a classical frog – a long-legged jumper with smooth skin. It is most common in wooded areas with abundant ponds, where you may find its big floating mass of around a thousand eggs in spring. You have to have one in the hand to see the conspicuous red colors on the underside of the legs and body. In the mountains and east of the Cascades you can find two related species, the Cascades Frog (Rana cascadae) and Columbia Spotted Frog (Rana luteiventris).

The Bullfrog (Lithobates catesbeianus [formerly Rana catesbeiana]) is one of the villains in the amphibian story. Brought from eastern North America for culinary and sporting reasons, this species seems to flourish almost anywhere it is introduced. Unfortunately, it does so at the expense of other amphibians and other aquatic creatures. A virtual eating machine, a Bullfrog will take in anything that fits in its capacious mouth, and it has been implicated in the decline of some other frogs that share its aquatic habitat.

One of the most interesting things about Northwestern frogs is their silence. Anyone coming from the East is used to frog choruses with multiple species calling, one of the real thrills of a rainy spring evening in Massachusetts or Florida or Missouri. But our frogs don’t say much. Although some toads have ear-splitting trilled calls, ours makes nothing more than chirps. Red-legged Frogs call from under water and can be heard only at very close range. In fact, our only noisy native frog is the chorus frog. Of course the introduced Bullfrog has added much to our soundscape, its loud jug-o-rum resounding from warm-water lakes all over the region.

The Tailed Frog (Ascaphus truei) is another silent species - it doesn’t even have ears. It lives in rushing streams, where almost any sound would be obscured by the sound of the water. Unlike many other frogs, the males don’t attract females by their calls, but instead go looking for them. They also can’t fertilize the eggs in the standard way by depositing sperm on them, as the current would wash the sperm away. Thus the males have evolved an extension, but it’s not a tail!

There is still much controversy about what has caused so many frog species all over the world to become rare or, in some cases, extinct. A special kind of fungus called a chytrid (Batrachochytrium dendrobatidis) is heavily involved, as infestations of this fungus can kill off all the individuals of some species in an area. Fortunately, our Northwest amphibians have not declined as thoroughly as have populations of many tropical montane species.

Dennis Paulson

IT’S SALAMANDER SEASON!

2010-03-17T09:34:00.000-07:00

Spring has sprung, or at least it’s about to spring, and it’s the time of year when amphibian activity becomes most noticeable.

Washington supports populations of 14 species of salamanders and 11 frogs. Amphibians like wet climates, and we’ve got that. Salamanders are diverse in temperate latitudes, frogs a bit less so, but as usual, the tropics are the home of the greatest diversity (compare Costa Rica’s 43 salamanders and 133 frogs!).

Our rainy winter provides the water to allow frog and salamander breeding, and as soon as it warms up enough in spring, off they go. This happens in late February or March for a variety of species.

Northwestern Salamanders (Ambystoma gracile) live underground for much of the year but come to the surface to feed in spring and during fall rains. They are rarely seen but could be observable at night at breeding ponds, when the adults come to the water to breed. Males court females, then when both are ready, the male deposits a spermatophore which the female picks up in her cloaca. The sperms within fertilize her eggs as she lays a big clutch of around 100 eggs in a jelly envelope the size of an orange, usually wrapped around some underwater object. The larvae stay in the water for a year or more, then undergo metamorphosis to the terrestrial stage and breed in the next spring.

Meanwhile, Long-toed Salamanders (Ambystoma macrodactylum) are migrating to other ponds, often smaller ones. This species is more common and wide-ranging, occurring in drier parts of the Northwest and well up in the mountains as well as the wet western lowlands. Breeding occurs in the spring, but females lay much smaller egg masses, averaging only a dozen or so eggs. Being a smaller species, metamorphosis and maturation are quicker than in the Northwestern.

Rough-skinned Newts (Taricha granulosa) are also stirring from their winter retreats and heading for the water. Like the others, they migrate mostly on rainy evenings to their breeding lakes. Courtship is prolonged, even lasting a day or more, but usually ending with spermatophore pickup, fertilization, and egg-laying. Eggs are laid singly in aquatic vegetation. The larvae metamorphose and leave the water in fall and disperse away from the water, to which they return after 4 or 5 years. In this species, many breeding adults remain aquatic through the summer, developing smoother skin and tail crests that aid in swimming.

By contrast, two of the common salamanders of the Northwest are terrestrial, with no aquatic stage. They are lungless salamanders, breathing through their skin! Western Red-backed Salamander (Plethodon vehiculum) and Ensatina (Ensatina eschscholtzii) live in forests, where they can be found in spring by turning over logs (be sure to replace divots!). They breed during winter, laying their 10 eggs in a cluster in such sheltered places, and the female guards them from invertebrate predators until they hatch.

Most of the other salamanders of the Pacific Northwest are locally distributed and uncommon, but they are worthy of attention by any naturalist fascinated by creepy-crawly critters. There is a good reference book: Amphibians of the Pacific Northwest, by L. L. C. Jones, W. P. Leonard, and D. H. Olson, eds., Seattle Audubon Society, 2006.

Dennis Paulson

CORMORANTS

2010-02-11T11:18:00.000-08:00

Cormorants are big black water birds with long necks. They dive for a living, and they float low in the water, with bill pointing up, while at the surface. All of them have all four toes connected by webs, characteristic of the Pelecaniformes, the avian order that includes pelicans and boobies. The bill is prominently hooked at the end, a “tool” to subdue the slippery fish they catch. All three species are fish-eaters, chasing down their prey with amazing underwater speed. At close range, their emerald-green eyes are a pleasant surprise.

Three species of cormorants inhabit Pacific Northwest waters. Two of them—Brandt’s and Pelagic—are entirely marine, and it would be a surprise to see either of them on fresh water at any time. The third—Double-crested—is one of the world’s more successful birds, occurring on all large water bodies, fresh and salt, all across the Northwest as well as throughout North America below the boreal zone. The other two species range along the Pacific coast.

Double-crested Cormorant (Phalacrocorax auritus) is the largest of the three and can be recognized by its yellow-orange face skin and throat pouch and somewhat pale bill. The feathers of the upperparts are very dark brown with black edges, producing a chevron pattern on the back. In breeding season, the adults have side-by-side curly crests. Immature Double-crests are the only cormorants that are pale beneath, the underparts becoming increasingly dark with age until they mature at three years.

Brandt’s (Phalacrocorax penicillatus) is a bit smaller, with a more slender bill, head, and neck and a distinctly shorter tail. The throat pouch is dark but becomes brilliant sky-blue in breeding season. The buffy patch around that can be seen all year. The back is glossier than that of the Double-crested, and the breeding plumes are white, arrayed along the neck and back. Immatures are dark brown above and a bit paler below but otherwise look like nonbreeding adults.

Pelagic (Phalacrocorax pelagicus) is much smaller than the other two, only half the weight of Double-crested, with a small head and very slender bill and neck. The plumage is iridescent, glossy green and purple. The tail is long, even longer than that of the Double-crested relative to the bird’s size. The throat pouch is dark, but the facial skin becomes red during the breeding season, fore-and-aft crests develop on the head, and a big patch of white feathers appears on either side of the tail base. Immatures are very dark brown, almost as dark as adults.

Breeding plumage in all species comes very early, so by February you can see signs of it, and they become easier to identify. After the birds are on their nesting colonies, even while still incubating eggs, they begin to molt the characteristic breeding plumage and are out of it by July or August.

At a distance, the three species can be difficult to identify, but the pale bill and throat of the Double-crested and the small size and glossy plumage of the Pelagic distinguishes them if they are anywhere near one another. And they often are, as they roost on pilings and rocks together all over Puget Sound. Double-crested is almost always much more common and usually perches higher than Pelagic. Brandt’s is less common in Puget Sound but still widespread in winter and often roosts with the other two. It looks about as large as the Double-crested but has a dark bill and throat and obvious short tail. Its head feathers often look puffy, in contrast to the flat head of the Pelagic.

Double-crested is the only one of the three that habitually spreads its wings to dry them as soon as it perches. One of the big puzzles in cormorant biology is why this behavior differs in birds with such similar habits and anatomy! Student research with salvaged cormorant carcasses at the Slater Museum was unable to find any difference in wetting or drying parameters in the three species.

In flight the Double-crested shows a thick, crooked neck. The Brandt’s neck is thinner and sometimes shows the crook but less pronounced. The Pelagic’s neck is straight, and the head is scarcely distinct from the neck. The shorter tail of the Brandt’s again is a good identifying mark. Double-crested often fly very high and often over land, probably going between lakes or between fresh and salt water, while the other two tend to fly just over the water. The two large species sometimes fly in small groups, usually arranged in a line; Pelagics fly by themselves or occasionally join groups of Brandt’s.

Cormorants in general feed on bottom fish such as sculpins, soles, and gunnels, which they pursue in all marine habitats. Pelagics tend to be more associated with rocky areas, Double-crested everywhere. Brandt’s tend to feed in open water on surface and midwater schooling fish such as herring and sand lance. Both of the larger cormorants often collect in groups to feed on abundant fish, while Pelagics tend to forage singly.

The most exciting way to view cormorants is at a breeding colony. All three breed in Washington, Brandt's on cliffs at the mouth of the Columbia River and the other two widely on cliffs (Pelagic) or islands (both) on the outer coast and in protected waters, south very locally into Puget Sound. The birds wave their heads around and hiss and grunt at one another, and their reptilian ancestry seems beyond debate. They lay 3-4 chalky white eggs and incubate them for about a month, then the young take another month and a half or more to leave the nest. Both parents participate fully in care for the young.

Dennis Paulson

A VOLATILE MIX

2010-01-11T14:57:00.000-08:00

Dunlins (Calidris alpina) are sandpipers that winter in large flocks at and near the Washington coast. Because they are common, they represent an important part of the diet of wintering bird-eating falcons (especially Peregrine Falcons and Merlins). When you find a large flock of Dunlins, there is every chance that one or more falcons will be nearby, and you may be gifted with one of nature’s more spectacular shows.

This is what happened to us near Edison in Skagit County on January 2, 2010. A large flock of Dunlins (around 4,000) was feeding and roosting in the flooded fields along the Bayview-Edison Road, not far from Skagit Bay, so we stopped to watch them.

Almost immediately the flock flushed, and a Merlin flashed through them. It didn’t get one, then disappeared, maybe because too many of its big cousins were in the area. In the hour and a half we spent at the spot, we saw three different Peregrines.

An adult male and an adult female stooped on the flock several times each, scattering the sandpipers like confetti. But it was confetti with a purpose, as the birds flushed and then became dense moving objects, oscillating back and forth over the landscape in alternating brown camouflage and white flash as they showed their upper- or undersides.

The speed at which the falcons went through the flock was breathtaking. The male seemed faster than the female, perhaps only an illusion because of his smaller size. After each pass, the predator would gain altitude quickly, then come back through in a dive. It would level out not far above the ground or water and come shooting through in level flight.

One would think any capture would be because of a random meeting in the air, but the falcon often jinked sideways or up or down slightly, presumably going after an individual bird each time. Their success rate was low; we never saw either bird catch a Dunlin, but a bit later we saw the female eating one, so she must have succeeded when we weren’t watching.

The biggest show was put on by a young female, easily distinguished because of her brown upperparts and striped underparts. She shot through the Dunlin flocks again and again, stooping perhaps 25 times as we watched. A lightning pass at eye level, sometimes coming within 50 feet of our car, then up and down again for another pass. She never picked one out of the air, but then we saw her circle around and pick one up from the water, presumably a casualty of her strike or a midair Dunlin collision.

We saw a Glaucous-winged Gull carrying a Dunlin in its bill, presumably another bird that hadn't survived the aerial confusion.

It was impossible to follow a stooping falcon with the camera lens, but by focusing into the middle of the Dunlins and hitting the shutter button just as the immature Peregrine passed, I managed to get a few photos during the attacks. The two adults obligingly posed for photos on nearby utility poles.

There was also a nearby Prairie Falcon that we never saw harass the Dunlins, perhaps because it already had something for lunch. A male Northern Harrier also passed through the waves of Dunlins but with no luck.

What a way to begin the New Year!

Dennis Paulson

SWANS IN THE FARMLAND

2010-01-06T10:15:00.000-08:00

The Trumpeter Swan (Cygnus buccinator) formerly bred widely across the North American boreal forest, but by early in the 20^th century it hovered on the brink of extinction because of overhunting, Since then it has been rigorously protected and managed, and it has bounced back and continues to increase.

When I arrived in Washington, we made special trips up to the Bellingham area to see Trumpeters at one of a few lakes where small wintering populations persisted. With four decades of additional protection, now thousands of them can be found wintering all over western Washington. It’s nice to have as many pluses as we can to compensate for the many minuses we suffer in overall biodiversity!

But we also have another species of swan in Washington, the arctic-breeding Tundra Swan (Cygnus columbianus). That species has remained more common over the years just because it is much more wide-ranging, but its populations seem more or less stable now, not increasing like those of the Trumpeter.

Nowadays both of these swans can be seen in large numbers in winter in northwest Washington. Trumpeters tend to winter on wooded lakes, Tundras on salt water or larger, open lakes, but here in Skagit and Whatcom counties, they find most of their food in farmlands. Some of these farmlands are managed specifically for the swans and Snow Geese that furnish spectacular displays of white winter waterfowl.

The two swans tend to forage in single-species flocks, but they also mix from time to time, usually a few of one species associated with a larger flock of the other. How do we tell them apart?

Tundra Swans are only about two-thirds the size of Trumpeters, as measured by weight, but they have to be seen in close proximity to be compared in this way. Their linear measurements are not so different, and all swans look big!

Most Tundra Swans have a small yellow spot between eye and bill, lacking in Trumpeter, but some Tundras lack that spot and look much like Trumpeters. The best way to distinguish these birds is by looking at the base of the bill adjacent to the eye. That area is broad in Trumpeter, so the eye looks like part of the bill, while it is usually distinctly constricted before the eye in Tundra, making the eye stand out.

This different configuration of the bill can present a different appearance at a distance, even in flight.

Being larger, Trumpeters may mature at a slightly later age, and they change more slowly from the gray immature to the white adult. In their first winter, Tundra Swans molt in many white or whitish feathers, so by midwinter the immatures are quite whitish. Trumpeters don’t do this, so by midwinter they are still leaden gray. Thus looking at the immatures is a good way to identify the species present in a flock. Even the whitest immatures are easily distinguished from adults by their dusky head.

Finally, the swan species have very different voices. That of the Trumpeter is a low-pitched sound that could be compared with an off-key trumpet. That of the Tundra is a higher-pitched honking, somewhat more musical than that of the Trumpeter, that might be likened to a flock of geese.

Dennis Paulson

5,000+ bullfrogs dying in desert potholes

2009-12-19T14:57:00.000-08:00

At Potholes Reservoir, Grant Co, Washington I discovered a rather dramatic scene of thousands of bullfrog tadpoles that were trapped in drying mud holes on 29 Aug 2009 (Photo 1). The small mud hole at the top right was about 3 ft and the larger in the middle of the picture about 12 ft in diameter. The larger contained approx 5,000 bullfrog tadpoles based on counts of a few subsamples; most were dead. The two mud holes in the photo had water about 4” deep a week prior to the photo and the surface quivered with wriggling tadpoles when approached.

Typically bullfrog tadpoles in the Northwest remain in ponds for at least one winter and grow to a total length of about 130 mm+ before morphing into froglets. Most of the tadpoles had small to medium size hind legs and were less than 110 mm in total length, which is the lower extreme of the size when bullfrog tadpoles could morph (Photo 2). Under normal conditions with plenty of food and no crowding, the tadpoles in the picture would be about one year old, but if food limited or crowded, they could be two years old. Although most were not ready to morph, a few had started the process and were hopping away from the drying mud holes. The closest pond was 100 ft away, but with the heat and predators, their chances were not good (Photo 3 and 4). The mud recorded tracks of great blue herons, great egrets, killdeer or yellowlegs, coyotes and black-billed magpies (Photo 5). Yellowlegs have small mouths, but eat the tadpoles by vigorous shaking the tadpoles to pieces.

The dead and dying tadpoles illustrate one limit to this invasive species’ success – they can’t survive in ephemeral ponds. Although the area is flooded as the level of the reservoir rises during winter and spring, as the water level drops through the summer, they move to deeper water. The mud holes were at a low spot so presumably the tadpoles moved to the deeper water as the water level dropped through the summer, but they moved to the wrong pond and were cut off.

Bullfrogs have recently expanded into the main reservoir and are now extremely common in Crab Creek beaver ponds and in ponds near Job Corp Dike, which is at the NW corner of the reservoir. There were none in 2002, but tadpoles starting showing up in traps in 2006, and 2009 was the first year I observed adult and juveniles widespread throughout the region. One 12 m dia pond at the Job Corps Dike had over 100 frog heads visible as they floated on the surface waiting for a prey object to venture near (Photo 6). There were none at Dodson Road/Winchester Wasteway (10 mi to the west) or at I-road/Frenchman Hills Wasteway (16 mi WSW). They were recorded in lower Crab Creek, south of O’Sullivan Dam, prior to 2005 (WA Gap analysis). The species was introduced into Washington from east North American in the 1920-30’s for food, sport and for pond features and have since spread throughout lower Puget Sound and the Columbia basin and are slowly spreading into new regions such as Potholes Reservoir.

It is generally assumed that the bullfrogs are harmful to native species. But at Potholes Reservoir, they are simply joining other introduced species in the reservoir such as large and smallmouth bass, yellow perch, pumpkinseed, and bluegill that I caught on the same trip (Photo 7). Additional introduction include are catfish, carp, crappie, and rainbow trout. In prior years, I found Pacific Chorus Frogs common around the beaver ponds and leopard frogs rare, but always present. I found neither of these species in 2009 searches, and it is possible they were supplanted or eaten by more common bullfrogs.

I happen to like bullfrogs and felt for the little guys as they struggled to survive, but that’s life in the desert. They were all turned into tadpole jerky by the sun and are now in December probably providing coyotes and magpies with snacks.

Gary Shugart