POORWILL, BEAUTIFUL BIRD OF THE NIGHT

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

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

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

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

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!

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!

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