SNOWY OWL FLIGHT YEAR

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

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

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

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

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

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

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