Cooperative breeding in corvids (Passeriformes,Corvidae)

The family of corvids differs from most other passerines by the significant number of species (at least 33) in which the feeding of nestlings and fledglings involves not only parents, but also individuals from their already grown broods (one-year-old and older). A review of the currently known data on cooperative breeding (or helping behavior) in corvids is given. This paper discusses factors that can contribute to the manifestation of delayed dispersion of young birds and the appearance of their helping behavior. It emphasizes the importance of long-term social bonds between parent birds and their offspring in delayed dispersion. At the heart of such social relationships is the tolerance of adult birds to their offspring and prolonged care for the young birds. The appearance of irregular helpers near the nests may be a prerequisite for the emergence of the helping behavior in certain family groups and populations.