A few birds from the Yukon-Kuskokwim Delta.
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Arctic Warbler:Arctic Warbler Cungakcuarnaq I was camping with one of my grandsons last week along the Denali Highway and spotted a couple of Arctic warblers. It reminded me of the Arctic warbler family I saw one August when Jennifer and I were teaching in Emmonak in 1989. I had never seen these birds before and wanted to learn more. When I saw them last year in the Anaktuvuk River Valley in northern Alaska, then last week with my grandson, I thought, I’m going to write about this little bird and share some of the new information about them. First off, it’s not really related to American warblers at all. It’s considered an “Old World Warbler” in the Silviidae family and more closely related to kinglets and gnatcatchers. You get a hint of that when you first hear their song, which is very unlike the melodious songs of true New World Warblers. Their song, in contrast, sounds to me a little like that of a locust buzzing (although with variations) in the desert of the Southwest. Although this bird is a transplant from Asia, it only nests in Alaska for three months, then heads back home to its wintering grounds in Southeast Asia, especially in the Philippines. Its favorite nesting habitat in the YK Delta, as elsewhere in Alaska, is in thickets of willow, dwarf birch and alder scrub, mostly along streams and at the edge of ponds. If you watch the birds closely, you’ll see they feed in the same way our New World Warblers and other insect-eating birds do, although they do have the habit of searching a little more carefully under the leaves of small trees for their prey. And they have the same gourmet tastes, eating everything from mosquitoes to leafhoppers, caterpillars and spiders. Food is, of course, the primary reason why this species has spread to Alaska. Since we have so much wild country here, we have a lot of bird food. When Arctic warblers first arrive on their nesting grounds in Alaska the male immediately gets down to the serious business of establishing his territory and singing furiously to defend it. In really serious encounters with other males, the property owner may flap its wings slowly while singing. During this intense period of trying to attract a mate to his important little parcel of land, the male will often vary the pitch and tone of his song to make it sweeter for his potential paramour. After she has decided on her mate, the female alone builds her nest on the ground, usually in a mossy area, or in the side of a grass tussock, under a dense canopy of mixed shrub species. The nest is so well hidden that predators, including scientists studying the bird, have an almost impossible time finding it. If you ever do find it, you’ll see that it is in the shape of a dome (a little like a dipper’s nest) with the entrance hole on the side. She builds it artfully of dead grasses, moss, and leaves, then lines it with fine grass and animal hair. She lays up to seven white brown-dotted eggs and broods them for 11-13 days. If a predator is heard or seen skulking about, the female will jump off her nest, begin scolding like a wren and even perform a “broken-wing act” to distract the skulker. As soon as the eggs hatch the male stops singing so furiously and begins to help his partner feed the youngsters. By this time there are lots of insects crawling and flying around to be caught and fed to the quickly growing baby birds, and after a couple of weeks the young are big and strong enough to step out of their little hobbit house and fly away. At that point, they learn quickly from their parents how to feed themselves and fatten up for one of the most epic migrations of any songbird on earth. Only three other songbirds that nest in Alaska migrate in the same direction (Bluethroat, Northern wheatear and Yellow wagtail), over the Bering Strait and southeast across Siberia down to the warm country of southeast Asia (and for the wheatear all the way to sub-Saharan Africa). Most Alaskan Arctic warblers end up in the Philippines. They do not migrate southward in North America. The Yup’ik name for the Arctic warbler, Cungakcuarnaq, is the same as for the Wilson’s and Yellow warblers. It literally translates as “little greenish-yellow bird.” Its Western scientific name, Phylloscopus kennicotti, refers to its habit of peering under leaves for insects.  |
