A VOLATILE MIX

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

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

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

A COOT IS NOT A DUCK!

Next time you’re at the water, whether salt or fresh, watch for a ducklike bird with a gray body, darker head and neck, and white, chickenlike bill. You’re seeing an American Coot (Fulica americana). Coots are often thought to be waterfowl (i.e., a duck), but they are not. They are in the rail family, in the same avian order as cranes. These birds are only distantly related to waterfowl.

Coots are nonetheless interesting, even though they’re not ducks. They are rails that look like ducks because, over evolutionary time, they have come out of the marshes where rails are common and have become adapted morphologically and behaviorally for living a duck’s life. They swim like a duck and dive like a duck, but admittedly they don’t quack like a duck! The chickenlike bill is quite different from that of a duck. Ducks have sieve-like lamellae on the edges of their bill to allow a sort of filter-feeding, while coots just grab their prey items and swallow them.

To be able to swim well, coots have evolved lobed toes, much like those of grebes. Gallinules and moorhens, which are also rails and look much like coots, haven’t evolved the lobes, and they are rather intermediate between rails and coots, able to swim with their long toes even though they aren’t webbed or even lobed. Coots forage at the surface, dip below it somewhat as ducks do, and dive underwater in deeper water. They don't stay down very long, popping up like a cork after a brief visit to the nearest vegetation.

Coots breed locally in the Puget Sound area but more commonly in the dry interior, where they are on most freshwater wetlands. They prefer ponds and lakes with both dense marsh vegetation, from which they get material to construct their nests, and plenty of open water, where they feed. They migrate to larger lakes in the winter, where they form flocks, sometimes large ones. Poor fliers, they migrate at night, probably to avoid predation by bird-eating hawks.

Coots are much more tied to a herbivorous diet than are rails. Their principal foods in fresh water are pondweeds, algae, sedges, and grasses, although a wide variety of other plants are taken. Filamentous submergent plants seem to be favored overall. They also eat small numbers of freshwater invertebrates, especially in the breeding season. The young are fed almost entirely on animal matter. When seen in small numbers on salt water, they may be utilizing green algae such as sea lettuce.

Coots also leave the water to graze on land, and they are commonly seen doing so adjacent to city park lakes. They retain some of their rail heritage in being better walkers than ducks, and when disturbed, they can run over land. They are much less well adapted to flight than ducks are, and they have to make long take-off runs to get off the water, and then fly awkwardly. When Bald Eagles harass them, they cannot escape by flying, and a pair of eagles can tire out a diving coot fairly quickly and then share the meal.

Coots are feisty birds, very territorial in breeding season and inclined to chase just about any other birds of their own or other species away from their nesting areas. They display with both their white bill and white undertail coverts, then they may fight fiercely, locking feet and pecking each other. They do manage to get along with their mates, and they make big, sloppy floating nests out of marsh vegetation. They lay a lot of eggs, a typical clutch size being around 7 but often up to 10 or more. The young are semiprecocial, able to get around on their own but still having to be fed by the adults. They are strikingly colored in comparison with the drab adults.

Dennis Paulson

it's waterfowl time

Fall is the time when thousands of waterfowl (ducks, geese, and swans) move into the Pacific Northwest from farther north and east. Vast numbers of these birds breed in Alaskan and Canadian wetlands, far enough north that these wetlands freeze each winter, and the birds move ever southward as their habitats freeze from north to south.

The first to come in are the dabbling ducks of interior marshes. Flocks of Northern Pintails, American Wigeons, Green-winged Teals, and others begin to arrive in late August. When they come, they all look like females, the males still in the eclipse plumage that camouflages them while they molt all their flight feathers on the breeding grounds. But by October many of these males are in their distinctive and showy breeding plumage, which they wear through the winter and into the next summer.

Meanwhile, large numbers of scoters have been appearing at Northwest coastal locations, where they undergo the same flight-feather molt that the dabbling ducks undertook on their breeding grounds. Many of them remain for the winter in the same areas, even north to Alaska, as marine environments are more resistant to freezing. In October, many of the diving ducks that have completed their molt in northern waters arrive. These birds feed in deeper water, and deeper water bodies freeze more slowly than shallow ones, so they can remain longer at high latitudes. This group includes scaups and Canvasbacks and their relatives, as well as many more scoters.

Migratory goose flocks, which begin to appear in late September, peak in October. They include Snow Geese from Siberia and Canada, Cackling and Greater White-fronted Geese from arctic and subarctic latitudes in Alaska and western Canada. These birds, in their V-formations and lines, are the most impressive migrants, but duck flocks, especially on the outer coast, can be impressive as well.

Finally, in November the last of the diving ducks begin to appear, including Buffleheads, goldeneyes, and mergansers. These birds stay as far north as they can as long as they can, but eventually they are driven out by the freezing of the larger lakes. By this time Trumpeter Swans from southern Alaska and Tundra Swans from farther north have appeared on our wetlands.

Many waterfowl continue their migrations beyond the Northwest, but so many of them stay here through the winter that this is close to the best, if not the best, region on the continent for ducks, geese, and swans. It’s time to go out and see for yourself.

Dennis Paulson

mammal watching can be fun

Many of us are birdwatchers (or birders, is there a difference?), but not so many are mammal watchers (mammalers?). But mammal watching can be fun too. There are only about half as many species of mammals as there are of birds, so there aren't as many to watch, but—of great significance—the vast majority are brown, so they don't attract the attention of those who love to see the varied colors presented by birds. Many birds are conspicuously, even rainbowly, colored. So the mammals have one strike against them (of course, we're one of them, surely a strike for them).

Perhaps of even greater significance is the fact that most mammals are nocturnal, and most of us do our nature study during the day, when we can see what's going on. Mammalogists know that if they want to have a lot of encounters with mammals, they go out at night. And they have to resort to a whole array of technology, from flashlights to mist nets (for bats) to sunken cans (shrews and mice fall in them) to live traps (especially for rodents).

Nevertheless, there are mammals that can be seen during the day. This includes all marine mammals, most ungulates (hoofed mammals), and some rabbits and rodents (especially squirrels). A trip to a big national park, where they are protected, may tally a surprising number of mammal species.

We found a few of these mammals, totaling seven species, on an early October trip to the Washington coast. Among them was a small herd of Elk consisting of a finely antlered male and two cows and their half-grown calves. Elk seem to be increasing in the Pacific Northwest, both the Roosevelt Elk subspecies on the coast and the Rocky Mountain Elk of the Cascades and East. There are small herds of Elk all over the southwest corner of the state, often visible in late afternoon as they come out of the forest to graze on herbaceous vegetation in prairies and second growth.

Of marine mammals, we saw quite a few Harbor Seals and California Sea Lions at the mouth of the Columbia River and the mouth of Grays Harbor. One big male sea lion was sleeping on a floating dock in the harbor at Westport, quite unconcerned with fishermen, crabbers, and tourists walking past about 20 feet away. As we watched, it had a good scratch, much like you'll see your pet dog or cat doing. From a population low some years ago, California Sea Lions have become more and more common, and the people who work in the harbor at Westport have become concerned as more and more of the big (and dangerous) mammals pre-empt parts of the docks.

Of rodents we saw numerous Douglas Squirrels, the common native squirrel in western Washington forests. Of lagomorphs (the rabbit order), we were enthralled by a baby Snowshoe Hare that grazed on weeds at the edge of the road in Leadbetter Point State Park. Unlike many of its species, this little gem sat there and fed calmly as we approached closer and closer with our cameras. It's a great feeling to get to photograph any wild mammal at leisure!

It's always special to see carnivores, and we saw two of the more common species of Washington. We watched a Coyote come out of the bushes at Leadbetter Point, trot over to the shore of the salt marsh, and lie down right at the water's edge. It was engaged in grooming rather than hunting, although it seemed to us that it was looking intently at a nearby foraging Great Blue Heron.

Finally, there is a nice viewing platform on the rocks in Westport where you can look out over the harbor with a scope and take in the bustling avian activity. Local people put out food and water for a crowd of feral cats there, and I wonder if they know they are feeding native carnivores as well. A Raccoon came out of the rocks as we watched and meticulously cleaned up a pile of cat chow, then finished with a drink from the water bowl and ambled back into the rocks. Not a bad day for furry encounters.

Dennis Paulson

Mother Nature's art gallery

Among the many signs of seasonality, one of the most spectacular is the display of beautifully colored leaves that tells us that the season must be autumn. This painting spree by Mother Nature lasts for one or two months and then is gone. When a child asks why the leaves change color in the fall, the question ranks right up there with "why is the sky blue?" It's one of those things of the world around us that we accept without questioning, unless we're a child or a scientist set on finding the answer.

Botanists have figured out how this works. As the days become shorter, plants with deciduous leaves stop producing the green pigment chlorophyll, and the chlorophyll already present in the leaves begins to break down. Carotenoids that have been present as insoluble pigments in the plant's chloroplasts are then exposed as the bright yellows that we see in cottonwoods and aspens and bigleaf maples.

The brilliant reds are produced quite differently. The autumn drop in temperature reduces the transport of sugars out of the leaves, and in some trees the excess sugar is used to synthesize anthocyanins, the same pigments found in red flowers. This happens in our vine maples, our blueberries, and our mountain ashes, among others. A combination of anthocyanins and carotenoids produces the range of colors that we see in many species.

Even knowing the "how," have we answered the "why?" Is there any advantage to a plant in having these colors in its leaves in the fall? That question remains to be answered. Perhaps this particular phenomenon has no adaptive significance. But perhaps it does!

Autumn is a time during which nature can be enjoyed at a distance; just look at forests or tree groves or individual trees in a park. In New England, the whole world changes color. In the Pacific Northwest, the brilliant reds and yellows of the deciduous trees are scattered through landscapes of evergreen conifers.

The color change is very different in different groups of plants. Red alders are prominent in our Northwest forests, but they contribute nothing to the fall extravaganza, the leaves merely turning brown and then dropping from the tree. This leaves many of our westside forests rather dull except for bright spots of red vine maples and yellow cottonwoods. For total immersion in autumn colors, a resident of the Puget Sound area should head into and east of the Cascades.

Dennis Paulson