Annual Cycles of Northwestern Siberian Warblers (Passeriformes, Sylviidae) and Their Transformations during Subarctic Warming

摘要

Features of the annual cycles of warblers from the lower Ob and the Yamal Peninsula during the development of high latitudes are compared. The invasion of the yellow-browed warbler, the greenish warbler, and the accentor into the Subarctic is limited by arboreal vegetation, and the invasion of the arctic warbler is limited by tall willows in the river valleys of the middle Yamal. The northwestern Siberian warbler, chiffchaff, and sedge warbler inhabit the subarctic tundra of Yamal. The last three species move northward. There are no species or subspecies of warblers associated with the Subarctic, but the birds tolerate temperatures close to 0 degrees C, allowing the northwestern Siberian warbler and chiffchaff to come in the second half of May and early June. Sedge, arctic, and yellow-browed warblers coming in June are more thermophilic. The probable advancement of forest-tundra landscapes to the north under conditions of further warming will entail the northward movement of forest and shrubby birds-not only warblers-because there are no factors preventing it.