Completeness of seasonal molting in passerine birds (Aves, Passeriformes) in Northwestern Siberia

Abstract

This paper considers the variability of the completeness of seasonal molting in passerine birds of the forest tundra and tundra areas of Western Siberia. All variants of passerine birds of North Eurasia known for molting—from complete postjuvenile molting at hatching places to its absence and complete postjuvenile molting at wintering places or at migratory routes, from complete prebreeding molting at wintering places to its absence, and from complete postbreeding molting at nesting places to complete molting at wintering places or at migratory routes—are shown. The factors affecting the completeness of molting are discussed—the properties of adaptation to the subarctic region, length of the migratory route, and photoperiodic conditions during molting. The completeness of molting is most significantly affected by the duration of daylight.