A few birds from the Yukon-Kuskokwim Delta.
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Yellow Wagtail:Yellow Wagtail Ikigcaqaq Here’s a mouthful for you: Motacilla tschutschensis. That’s the new scientific name for this bird, and it’s almost as long as the bird itself. It means, “the bird that bobs its tail up and down.” None of the Yup’ik names I‘ve found are that long, and the one I was given from Scammon Bay, Ikigcaqaq, I think better describes this wagtail than the scientific or English common names do. Ikigcaqaq translates as, “the bird that bends over, sticking his butt in the air.” Watch it sometime and you’ll see what I mean. What some authors describe as simultaneous head nodding and tail bobbing is what I liken to the “dude strut,” a form of walking you find especially among “cool dudes” in the inner city. Whether it’s in willow thickets of the Lower Yukon Delta or the Arctic National Wildlife Refuge (where I’ve seen most of these birds), the Yellow wagtail is a songbird that’s hard to miss. The bright yellow coloring of the male, its nodding head and bobbing tail with flashing white outer feathers, its loud sharp ple, ple, ple, ple song while flying or perched on top of tall willows, its pursuit of insects in midair, and the way a nesting pair (joined by other males) will aggressively mob an intruding predator (or bird watcher), are only some of its remarkable behaviors. Another is its aerial courtship flight. As soon as the birds reach their nesting territory the male begins courting the female. He flies up in the air about 60-90 feet, then floats back to earth on stiff down-turned wings, singing and slowly spreading and elevating his tail. Close to the ground, he glides over to a bush or high rock, sings, then repeats the ritual. The female is watching his display somewhere nearby on the ground or in the air. Sometimes the male may land near his paramour on the ground and crouch low with drooped wings and tail, body feathers all fluffed up, then run around her like a madman. He may also hover over her with his tail feathers spread wide. It’s an amazing spectacle, and soon accomplishes its purpose, and the pair seriously settles into a nesting mode. The female alone builds the nest on the ground in a well-hidden spot at the grassy base of a shrub, or at the edge of a tundra tussock. She carefully constructs it in the shape of a cup, using leaves, moss, lichens and grass, then lines it with feathers and animal hair. She lays as many as six buffy-gray eggs dotted with brown. Both parents help incubate the eggs, although the female carries more of the load, and after the eggs hatch in 11-13 days, both parents also feed the nestlings until they’re ready to depart the crowded nest about 13 days later. Since the young are not able to fly for another 3-6 days after they leave, the parents keep close eye on them and brood them during the cool hours of the Arctic twilight. During this period the young learn to hunt insects, small worms, snails, seeds and berries on the ground or along the edge of shallow water. Later they will become adept at hunting insects by hovering near foliage or chasing them in midair. As with other Arctic nesting species, they have only a short window of opportunity to fatten up for their long migration, which will take them all the way to Australia and parts of south Asia. There are several other Asian species of Yellow wagtail, but only the Eastern Yellow wagtail (tschutschensis) nests in Alaska. Even the Alaskan species originated in Asia, and only recently did it separate from its cousins and begin to nest in Alaska. It began doing this in the Bering Land Bridge area about 18,000 thousand years ago during the Pleistocene glaciation when earth’s climate was much cooler and the emerging land mass supported a tundra-steppe vegetation, a lot like what much of the Lower Yukon Delta looks like today. Later, as the climate warmed and the Bering Land Bridge was covered with water again (about 10,000 years ago), the continental land connection was broken, forcing the Alaskan species to breed primarily on the western and northern coasts of Alaska. Concentrations of spring and fall migrants on St. Lawrence Island and the Seward Peninsula are an indication of the age-old ancestral migration routes that had developed before the most recent flooding of the area that is now known as the Bering Sea.  |
