LAUSR

The clutch size of passerine birds of 39 species in 3797 nests is considered. The dependence of the number of eggs in nests of northern passerine birds on the pattern of their distribution within the tundra zone and on the size of ranges, as well as the relationship of the trend of variation in the clutch size of species with different patterns of adaptation to the Subarctic, are discussed. Differences in clutch size between species nesting in different geographic zones and at different latitudes from the Ob forest tundra to northern Yamal are analyzed. The dynamics of clutch size during the nesting season and size of the first clutches, repeat clutches (that replaced the destroyed ones), and normal second clutches is described. The rule known for birds of temperate latitudes was verified for tundra passerine birds: “the earlier the onset of breeding, the larger the clutch size”.