RESUMO
Long-term studies on the winter population of birds in the West Siberian Plain on a landscape basis allowed us to reveal the regional and seasonal patterns of their distribution. The highest proportion of species demonstrated forest-steppe and forest preference, while the lowest proportion demonstrated aquatic-semiaquatic and tundra-forest-tundra preference. The preference zones did not change or extend in the winter period relative to summer postnesting period only in a small fraction of species; while the preference zones of most species were reduced or shifted. Commonly, the zonal borders of preferred habitats shifted southward to better climatic, feeding, and safety conditions. Only rare species with seasonally changing and specialized feeding demonstrated a northward shift of these borders.
