On the basis of long-term researches (2010–2014) the population of birds of a right bank of a headstream of Angara River are considered stuffs on a diversity of birds in the winter season. It is shown that the greatest abundance reach the settled and some migratory of birds going here on a wintering ground. The headstream of Angara River during winter time concerns the most productive ecosystems of the Baikal Lake. It is caused by formation here very large «cold» wintering grounds of a waterfowl. The settlement territories of diffusive type is differed by greatest specific richness and a diversity of birds while forest ecosystems the close friend is enough the friend to this indications. As a whole, for terrestrialecosystems of this area of the lake Baikal the average level of specific riches, the Margalef index D_Mg = 13,1 and the Shannon diversity index H' = 2,42, and also rather low uniformity of the population (Е = 0,57) and high level of domination of few numerous species (1-D = 0,86) are characteristic. Such birds diversity in the winter season, most likely, is the most typical for boreal forests of Northern Asia.