PELAGIC BIRDS ARE OUT THERE

Most people have heard of albatrosses; few people have seen them. But every summer they are common offshore visitors to the Pacific Northwest. Boat trips out of Westport, Washington, and Newport, Oregon, go out 20-30 miles and can dependably find albatrosses and a host of other pelagic birds. Pelagic means “out of sight of land,” and there are a lot of pelagic birds. Because birds can fly, they roam all over the ocean’s surface in search of food.

Of course, all birds lay their eggs in nests on land or floating in freshwater wetlands, so you wouldn’t think they would wander far out in the ocean, but in fact they do. Many species fly thousands of miles when they are away from their breeding grounds for half the year or more. Black-footed Albatrosses breed in the Leeward Hawaiian Islands, but they roam to our coast, 3000 miles away, when not at home. Even more astonishing, when feeding young a Laysan Albatross may fly from the same islands up to Alaska’s Aleutian Islands, 1500 miles away, on a single multi-day foraging trip!

Sooty Shearwaters fly several tens of thousands of miles on their migrations from their breeding grounds in New Zealand to their wintering grounds in the North Pacific, taking an extended figure-8 path that has them flying counter-clockwise around the North Pacific. Meanwhile, Pink-footed Shearwaters make almost as long a flight from islands off the coast of Chile.

The Northern Fulmars that visit us, on the other hand, breed in islands in and around the Bering Sea, so they have to fly south to approach our coast. The Fork-tailed Storm-Petrels we see offshore come from much closer at hand, the string of islands that stretch along the outer coast from off Cape Flattery to off Point Grenville.

All of these birds are in the order Procellariiformes, called “tube-noses,” because of their tubular nostrils. Members of this group all take their food from on or near the ocean’s surface. Some of them skim the surface, others dive down to several meters or more. They all feed on fishes, squids, and planktonic crustaceans—the larger the bird, the larger the prey. And they all have an excellent sense of smell, which helps them find smelly prey at sea and their nest site back on their home island.

These birds are supremely adapted for flying very long distances. Their long, narrow wings are perfect gliding surfaces. With any air movement at all, the larger species surf the wind, rising into it with the lift it provides, then falling off to the side to gain speed to turn and rise up again. Watch them on a windy day to see their roller-coaster flight over the ocean. And if you’re seasick-prone, you don’t have to go out on a boat. At times in summer you can see Sooty Shearwaters from shore in astronomical numbers.

Dennis Paulson

YES, WE HAVE VULTURES

We often think of vultures as big, ominous-looking birds sitting around the carcass of a lion-killed wildebeest in Kenya or lined up on rooftops next to a garbage dump in South America. But we have our own carrion-eating vulture in the Pacific Northwest, the Turkey Vulture (Cathartes aura).

Turkey Vultures occur throughout the tropical and temperate parts of the New World, from southern Canada to Tierra del Fuego. Those at the northern end of the range, in Canada and northern US, are migratory. Tremendous numbers of Turkey Vultures migrate through Mexico and Central America. The vulture migration over Panama in October has almost reached the status of a tourist attraction, as the birds wheel and climb above the high-rise towers of Panama City in the fall, along with Swainson’s and Broad-winged Hawks.

They return to Washington from their tropical wintering grounds in late March and April to occupy nest sites on cliff ledges or in broken-off hollow trees or other dark recesses, usually in remote areas well away from human disturbance. They lay 2 eggs that they incubate for about 40 days. The young remain in and near the nest for up to three months after hatching. Oddly, although commonly seen in the air, they are almost never seen at road kill, very different from the situation farther south.

These vultures are very often seen early in the morning perched with wings outspread, apparently to dry them out. Why this is so common in vultures and doesn't occur so much in other large soaring birds may be a mystery we never solve.

Turkey Vultures fly with their wings held up in a dihedral angle, which it turns out adds stability in turbulent air. They often fly close to the ground, so this is of great importance. As a wind current hits one side, that wing tilts up and the other down. As it tilts down, it approaches the horizontal, where lift is maximal, and that stabilizes it. Watch a vulture in windy conditions and see how it tilts from side to side.

Unlike most other vultures, Turkey Vultures have a well-developed olfactory sense. Field experiments have shown that they can find something as small as a dead mouse by its smell, even under a closed forest canopy. Watch a Turkey Vulture quartering on the wind, going back and forth as first one nostril and then the other picks up the smell of a carcass from upwind. By going back and forth as the smell gets stronger and weaker, they eventually home in on the spot.

At lower latitudes, where Black Vultures are abundant, they may use Turkey Vultures as their carcass finders, watching individuals of the other species and following them to the ground. The Blacks are also watching each other, so the stimulus from a descending bird spreads outward, probably for quite a distance. Blacks dominate Turkeys, so the Turkeys must be quick to take advantage of a “fresh” meal. In the forested tropics, the much rarer big white King Vultures may finally appear and scatter all the lesser birds.

Turkey Vultures have actually increased in the PNW in recent years, for reasons unknown. Are there more dead animals now? Are they being more successful on their wintering grounds? Were they reduced by DDT like so many other raptors and are still recovering? In any case, they are masters of the air and a pleasure to see in the sky.

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