Tuesday, June 16, 2015


Now that summer has come around, it’s time to look at breeding birds, of which we have plenty in the Pacific Northwest. One such group is the vireos, Vireonidae. Members of this family, at least out of the tropics, are quite plain, olive to gray-brown, perhaps with a bit of brighter greenish or yellow thrown in. Some species have a combination of eye rings and wing bars, others have a supercilium (pale eye stripe) and no wing bars.

We have two each of these types. Of the eye ring/wing bar group, Cassin’s Vireos have a white throat contrasting with a leaden gray head and bright white “spectacles,” while Hutton’s Vireos are duller, with no contrast in the head/throat area and a less conspicuous and broken eye ring. In the second group, Warbling Viros are dull gray-brown above, with the white supercilium their only conspicuous mark. Red-eyed Vireos are much more brightly marked, rather greenish above and with a gray cap and rather conspicuous dark lines above and below the white supercilium. This species is the only one of our vireos that doesn’t have a dark brown eye.

More interesting than the differences in appearance are the differences in ecology. Cassin’s breed in somewhat open conifer forests and are quite common well up into the mountains. Hutton’s breed in lowland conifer and mixed forests and are uncommon even as high as the foothills. Warbling breed widely in mixed forests with a high deciduous component, much more commonly to the east of the range of Hutton’s, and Red-eyed are characteristic of tall cottonwoods in riparian situations along rivers and around lakes.

Red-eyed and Cassin’s are birds of the canopy, while Warbling and Hutton’s are more typical of the subcanopy and even understory. The consequences of these differences are that each species has a habitat in the Northwest where the others usually aren’t found. This is the ecological separation, presumably by each species being best adapted to its own habitat and foraging height, that is discussed in ecology texts. Our vireos show it particularly well.

In addition, three of the species are migratory, moving out of the region in winter and wintering in Mexico (Cassin’s and Warbling) and even far into the Amazon Basin in South America (Red-eyed). These long migrations are typical of most of our insect-eating birds, which would have trouble finding food in the winter when most insects are hidden well away from a leaf-gleaning bird such as a vireo. Hutton’s is resident, on the other hand, apparently able to find enough to eat in the moist forests where it occurs. We are at the northern end of its range, and it is doubtful if it could be resident any farther north. Perhaps because it is the smallest vireo, it can find insects in places in which the larger species couldn’t forage.

Vireos build nests supported by their rims, often in the fork of a branch and often enough in the open that they are findable by an observant naturalist. They are also findable by female Brown-headed Cowbirds, brood parasites that parasitize a large percentage of vireo nests. Our vireos seem to be doing fine in spite of this.

Dennis Paulson

Tuesday, May 5, 2015


For more than a month now, Pacific Northwest outer ocean beaches have been the scene of a massive stranding of by-the-wind sailors, Velella velella. These little blue critters are washing up on our beaches by the billions. Each time a new high tide comes in, they are deposited at the upper end of the waves in windrows on the beach.

     Velella wrecks are commonplace on the Pacific coast, usually happening in the spring of most years. But this year has produced a bumper crop of them, many more than usual, from Vancouver Island to California. First noticed in August of 2014, they came in in stupendous numbers in the spring of 2015 with unusually strong onshore winds. They are everywhere in tropical and temperate oceans, but their strandings seem to be most common on the American Pacific coast.

     Velella is a colonial animal, each sailor made up of hydroids attached together under a chitinous float, the individuals thought to be specialized for prey capture, digestion and reproduction. A stiff semicircular sail projects upward from the float, so any breeze blows the sailor across the surface. The sail is set at a bit of a diagonal, so the Velella is actually tacking off the downwind direction. It is speculated that the direction of tacking is such that the animals are kept offshore for the most part, but changing winds can undo that safety factor.

     One of the most characteristic things about Velella is its beautiful blue color. The blue pigment is apparently a protection against harmful ultraviolet radiation from the sun that streams down through the day.

     Velella are typical cnidarians, possessing nematocysts in their tentacles that kill tiny planktonic prey, including crustacean larvae and fish eggs, and digest them in a central stomach area. This nutrition is shared among the individuals and is augmented by algae (zooxanthellae) in the colony that photosynthesize and produce organic carbon and nitrogen. In the class Hydrozoa, they are more closely related to hydras than to jellyfish, although not as closely related to Portuguese man-o’-war as previously believed.

     They feature alternation of generations, reproducing like typical members of the phylum Cnidaria. The sailors that we see bud off tiny medusae (“jellyfish”) that then produce male and female gametes that fuse and form larvae that at some point presumably assemble into the animals that we see. Exactly how this happens is still quite unknown, and the smallest ones that are usually seen are fully developed.

     You might guess that Velella, just because of its abundance, would be attractive as prey, yet much of the animal is inedible chitin, the same protein that makes up the exoskeleton of insects. Their best-known predators are spectacular pelagic nudibranchs (Glaucus) and a group of unusual snails (Janthina) called violet snails that produce mucus with their foot that forms into bubbles that support them. They float on the surface darkside up, countershaded like oceanic fish!

     Two jellyfish predators, ocean sunfish (Mola mola) and leatherback turtle (Dermochelys coriacea), are said also to consume Velella, but there seems little evidence for this. Many sandpipers fed among the Velella at Grays Harbor recently, and some poked into the tentacles, perhaps finding small prey among them.

     These Velella velella are not to be mistaken for the Seattle musical group of the same name!

Dennis Paulson

Tuesday, April 14, 2015


Beetles are the most diverse animals in the world, with surely over a million species, although only about 350,000 have been described to date. Any collection of tropical insects contains undescribed species, and beetles often make up a good part of this, even though they have been favorites with collectors ever since specimens were first collected for museums.

One explanation for the great diversity of beetles is their long association with angiosperm plants. It appears that a taxonomic group that is associated with these very diverse vascular plants has an unlimited array of niches available for speciation, furnished by both the many different species and their many parts—leaves, stems, roots, flowers, fruits—on which to specialize.

Long-horned beetles, family Cerambycidae, are strongly associated with these plants and one of the most diverse beetle families, with about 35,000 species known to date (1,200 or so in North America). Almost all of them have larvae that bore in plant stems. They are distinguished by—guess what—their long antennae as well as C-shaped eyes that curve around the antennal bases. They range in length from a few millimeters to over 17 centimeters and because of their size, beauty, and those looong antennae, are among the most charismatic and well-liked of beetles.

The family is common in the Pacific Northwest, and some of the species are striking. A large black and white one, the cottonwood borer Plectrodera scalator, breeds in cottonwood trees, so look for it along rivers with associated riparian forest. Originally distributed east of the Rockies, the species has become established in the Pacific Northwest.

The eggs of Plectrodera are laid in the fall, and the larvae bore into the bases of cottonwoods and willows. They pupate beneath the bark and emerge as adults in 2-3 years. The larvae may girdle and kill trees and are considered a pest in some areas.

The larvae of Monochamus scutellatus, the white-spotted sawyer, bore into pines and spruces, and the adults are attracted to trees that have been burned in forest fires. Apparently the burned trees release chemicals that attract the beetles from long distances. The species is considered an economic pest because the boring larvae make the wood, which might otherwise be harvested, unsightly, as well as allowing access to fungi. Wood-boring beetles cause the timber industry to lose millions of dollars annually.

The elderberry borer Desmocerus auripennis lays its eggs in elderberry bushes. The larvae bore in the stems just like their larger relatives do in trees. The locust borer Megacyllene robiniae is also native to eastern North America but has spread into the West with the planting of black locust trees. This and the cottonwood borer are spectacular species, and it’s a bit disappointing to find out that they came from somewhere else!

Check patches of milkweed for milkweed beetles, Tetraopes femoratus. A related eastern species is shown here. The larvae of these beetles live in milkweed stems, and both larvae and adults are distasteful because of the chemicals ingested with the milkweed tissue. The bright red coloration is surely an aposematic advertisement of this.

A very large number of species of cerambycids are flower visitors, eating the pollen and probably in some cases effecting pollination even as they destroy the reproductive efforts of the plant. Lepturobosca chrysocoma, Pseudogaurotina cressoni, and Xestoleptura behrensii are examples of this group. Many are brightly colored and tapered behind, perhaps giving them some resemblance to bees or wasps, especially in flight. By that mimicry, they fool some avian predators that normally leave stinging hymenopterans alone.

Dennis Paulson

Tuesday, March 3, 2015


I look at a lot of birds every year, and I don’t see many that are as cool as this one, a leucistic Black Turnstone (Arenaria melanocephala). This striking bird is wintering at the end of Sandy Point, north of Bellingham, Washington, in a flock of its relatives, and I finally got around to checking it out in February. I found the flock feeding on rocks at the mouth of the marina there.

What a bird! From a distance it looked entirely white, but at close range elements of the pattern became visible, most of them very subdued. The more or less straight line across the breast identified it as a Black rather than a Ruddy Turnstone (Arenaria interpres), which has a bilobed pattern of black there. There was also a Ruddy with the flock.

By comparing the bird with a normal Black Turnstone, I could see how much the melanin pigment was reduced on this bird, yet it wasn’t entirely absent. The darkest areas of normal pigment were on the rump and tail, but tan areas all over the bird, most readily seen in flight, gave me a good hint of typical Black Turnstone pattern.

The bird is definitely leucistic, not albinistic, because it has normally pigmented eyes. Albinism is the complete absence of melanin pigment. Because that pigment is what gives brown eyes their color, when it is lacking in an albino, the blood vessels in the eyes give them a bright red color. Leucism is a reduction of all pigments, but not necessarily their absence.

The bird presumably grew most of its feathers in July and August, the time of fall molt in Black Turnstones, so they were about six months old in February and showing their age. In comparison with nearby normal birds, the primary feathers were distinctly more worn. The tertials, the long feathers that overlie the primaries, were very worn, much more than on the other birds.

The bright orange legs of this bird contrasted with those of normal Black Turnstones, in which they are brown to dull orange. Presumably in normal birds, melanin masks what would be bright orange otherwise. The legs of Ruddy Turnstones are bright orange, and one wonders whether they would remain exactly the same in a leucistic bird.

Its behavior appeared to be the same as that of the other birds, and they must have accepted it as a flock member. However, when the entire flock flew away, startled by a jogger coming down the beach, the white bird flew in the opposite direction with two of the black ones rather than with the flock.

Such birds are extremely rare, and I feel fortunate to have seen this one. One thing special about it is that it could never be mistaken for another turnstone, thus always recognizable. If we could recognize all birds individually, we would know a lot more about them!

The white turnstone’s presence is being monitored closely, so we may know when it has departed for the north, assuming some local falcon doesn’t pick it out of the flock. It is well known that birds of prey will home in on odd-looking birds, as they are easiest to follow in a twisting, turning flock.

If it does persist into spring, local birders will be watching closely for it late next summer, when Black Turnstones return here from their breeding grounds in the Yukon/Kuskokwim River delta. Let’s hope it makes it back.

Dennis Paulson

Tuesday, January 27, 2015


For a unique and intimate experience with waterfowl and other birds, visit George C. Reifel Migratory Bird Sanctuary west of Ladner, British Columbia.

Reifel Refuge, as it’s called by many, is a 300-hectare (740-acre) plot of land on Westham Island on the Fraser River, about an hour’s drive from the metropolis of Vancouver. George Reifel bought the land in 1927 and established a family recreational retreat on it, creating waterfowl habitats as well as road access by a series of dikes and causeways.

In the 1960s, the Reifel family granted a lease to the British Columbia Waterfowl Society to create a bird sanctuary on the land. Helped by the management of Ducks Unlimited Canada, wildlife habitat was preserved and expanded with the provincial government establishing a game reserve on adjacent land. In 1972, the family further donated and sold the land to the federal government on the condition that it would be maintained as a sanctuary.

The government designated part of the sanctuary and the area adjacent to it, some 328 hectares, as the Alaksen National Wildlife Area. Some activities are permitted on this land but not the free access to the public that characterizes the sanctuary.

The sanctuary charges a nominal entrance fee and is open from 9 am to 4 pm every day. Sometimes it has quite large crowds, not a place to go if you want to get away from people for your nature experience. However, the high density of humans day after day is what has conditioned the birds to be as unafraid of us as they are.

The sanctuary was set up for waterfowl, and there is always a good representation of local waterfowl species, both dabbling and diving ducks. Large numbers of Snow Geese migrate through the adjacent wetlands, some of them remaining for the winter, and mostly those will be seen overhead moving between feeding areas. All the ducks present are somewhat used to people and will furnish close viewing and great photo opportunities.

There is a small population of resident Sandhill Cranes, most of them not pinioned, and some of them will feed from the hand. Some of them are good at gently taking seeds from an open palm, but be aware that you’re taking the chance of a poke with a sharp beak from those that aren’t. There are also Black-crowned Night-Herons roosting near the entrance to provide good looks at another unexpected species.
There are feeding stations everywhere, and during the winter they attract great numbers of seed-eating birds, for example Black-capped Chickadees, Red-winged Blackbirds, Spotted Towhees, Fox, Song, and Golden-crowned Sparrows, House Finches and House Sparrows. The chickadees are so tame that anywhere along the trails they will land on your hand if you open it with sunflower seeds on it. Occasionally a Red-breasted Nuthatch may do the same.

Brown Creepers and kinglets are also often seen, and like other birds there are quite tame. Quite a few other passerines inhabit the patches of woodland, and unusual visitors are seen with some regularity, for example Bohemian Waxwings and Pine Grosbeaks recently. And it’s always worth watching for less common sparrows such as Swamp, Harris’s, and White-throated along the path.

Because of all the feeders and seeds, rats and mice and Eastern Gray Squirrels (including the black morph, established in the Vancouver area) are also attracted to the area, and the local owls know it. A pair of Great Horned Owls is regularly seen, and there are always Northern Saw-whet Owls present, if very hard to see in the dense foliage where they roost. Other species of owls are seen from time to time, and there are usually hawks and falcons about, interested in the songbirds as well as the rodents.

You can buy sunflower seeds at the office and carry them around to feed to whichever birds you like. You may give them all to chickadees, as there is something wonderful about one of these tiny birds landing on your hand. You may be attacked by Mallards before you barely get going onto the trail, and Mallards are the most abundant and insistent ducks in the place. But look closely, and among the Mallards there will be at least a few American Wigeons and a few Northern Pintails.

More than these, there are Wood Ducks scattered around the area, and they too are interested in handouts if they can get to them before the omnipresent Mallards. They are shy enough that you’ll have to seek them out, but one way to feed them is to put seeds on top of fence posts, which the Wood ducks—tree dwellers that they are—can easily get to. Of course they have to beat the chickadees and Song Sparrows to them.

Dennis Paulson

Thursday, January 22, 2015


North America has the distinction of being the only continent on which a group of birds has evolved the ability to tap into the sap of living trees. These are the four species of sapsuckers (Sphyrapicus): Yellow-bellied (S. varius), Red-naped (S. nuchalis), Red-breasted (S. ruber) and Williamson’s (S. thyroideus). The first three replace one another from east to west across North America, while Williamson’s occurs with both Red-naped and Red-breasted in the West.

Sap flows through the xylem and phloem of a tree with a function rather similar to that of blood in animals. It’s not important in respiration, as it is in us, but nutrients and other chemicals circulate in it. It is full of sugars, presumably an important component of its nutritive value. Phloem sap of deciduous trees can contain concentrations of greater than 25% sugars in summer.

Sapsuckers dig holes in the bark of trees to get at this sap. They dig phloem holes, usually square and shallow, and continue to enlarge and add to these holes, excavating new ones above the old in a vertical arrangement. They also dig xylem holes, smaller and usually circular and penetrating the cambium layer to reach the xylem. These are arranged in horizontal rows. Some trees show both types of holes, easily distinguished.

As soon as these holes are dug, sap begins to flow into them, and they can then be considered sap wells. They continue to flow while temperatures are sufficiently high, but when air temperatures drop below freezing, the sap freezes in the wells and is then inaccessible to the sapsuckers. This is why sapsuckers are the most highly migratory of woodpeckers. As temperatures drop during the winter, many Red-breasted Sapsuckers, normally nonmigratory, descend from the mountains to appear in Pacific Northwest lowlands in numbers.

Sapsuckers may spend over half of their foraging time constructing and maintaining their sap wells. They seem to prefer tree species with higher sucrose content in the sap rather than those in which flow rates are higher. However, their wells have been found in about 1,000 species of woody plants, native and introduced.

They also feed on insects attracted to or trapped in the sap as well as additional arthropods captured on the bark or in the air. They also take some fruit and leaf buds. Insects are captured to feed the young, but the adults often stop at sap wells and dip the insects in sap before taking them to the nest. This may be for added nutritional value or to acclimatize the young to feeding on sap.

Numerous other species find these sap wells nutritious, including both birds and mammals. In the Pacific Northwest, species that I have seen coming to the wells include Anna’s and Rufous Hummingbirds, Downy Woodpeckers, Black-capped Chickadees, Ruby-crowned Kinglets, and Eastern Gray Squirrels. The wells may be especially important to hummingbirds, some of which actually follow individual sapsuckers to note the distribution of their wells. Sapsuckers actively defend their wells against some of these species, but each sapsucker has so many wells that this isn’t a very productive tactic.

The fact that there aren’t any sapsucking woodpeckers in the temperate forests of Eurasia is an elegant example of the idea that not all niches are filled. But of course sapsucking insects of the order Hemiptera (true bugs, aphids and their relatives) are everywhere in the world.

Dennis Paulson
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