Results of long-term (1963–2007) studying of spatial and specific structure, and reproductive success of the waterfowl of Prebaikalia are presented. Based of works in the several centers of mass nesting existence of distinctions in specific structure of dominating groups is established and their specificity and uniqueness is shown. For three centers of mass reproduction (Selenga river delta, Irkut river mouth and Oka river floodlands) the basic limiting factors are revealed and specificity of their influence on nested groupings of a waterfowl is shown. It is established, that average general success of reproduction for the long-term period in each nested center essentially differs. It does not allow to extrapolate results even of well planned and executed works on the near areas.