Birds are warm - blooded creatures. Average their body temperature is 41°C. This means that they can remain active in the cold season, but need more food. So many birds leave the snow-covered homes and sent to winter in warmer climates.
The main reasons why birds migrate in winter to the South, the lack of food and cold. Flights more typical kinds of high and middle latitudes in the tundra almost all bird species breeding in the taiga - three quarters of the species. The number of migratory species in a particular habitat depends on how sharply in them different feeding conditions in summer and winter. Thus, among the inhabitants of the forests and towns about half of the species are migratory, and among the inhabitants of the fields, swamps, reservoirs almost all kinds. Migratory birds among insectivorous and carnivorous, and less among granivorous. It is clear: if the grain in the winter can be found, the insects are absent.
But there are birds that cold uneasy. They all year round are at home right conditions for the existence and do not travel. These birds are called sedentary.
In the winter forest, you can hear busily knocking woodpecker, chirp titmouse, pikas, nuthatches, jays. Do not leave the winter forest and capercaillie, because he always has delicious pine needles. But the black grouse and hazel grouse eat alder catkins, buds, and juniper berries.
Amazing bird crossbill winter even manages to build a nest and hatch Chicks. Feeds Klest spruce seeds, which produces cones with his beak.
Some birds under favorable winter remain at home, and in severe winters wander from place to place. This nomadic birds. These include some birds nesting high in the mountains; in the cold season, they descend into the valley.
Finally, there are birds that under favorable winter conditions settled, but in bad years, such as when the harvest of the seeds of conifers, fly far beyond their breeding homeland. It whirred, tit-tit, Orekhovka, Redpolls, Robins, jays and many others. Just behave nesting in steppes and semi-deserts of Middle and Central Asia Saji.
WINTERING AND WANDERING BIRDS
Some of the widespread species of birds in some places migratory, while others have settled. Among doves are migratory, nomadic and sedentary birds. Hooded crow from the Northern regions of the Soviet Union flies overwinter in the southern area, and on the South, the bird settled. Blackbird we - migrant, and in the cities of Western Europe - settled. Rooks in more Northern latitudes, migratory birds, and in the South, for example, in Ukraine, in the Central region is settled. House Sparrow in the European part of the USSR lives all year round, and from Central Asia migrate to winter in India.