Cooperative breeding among Chinese passerines: inference from social behavior, diet, and migratory status

Recent estimates suggest that 9% of bird species are cooperative breeders. However, little is known about the breeding behavior of many species, particularly those in the Indomalayan and Neotropical regions. Our objective was to provide an overview of the prevalence of cooperative breeding among Chinese songbirds. Examination of the social behavior, diet, and migratory status of 55 known cooperative-breeding species of songbirds in China revealed that 90.9% live in small groups, 89.1% are residents in at least one or all their subspecies, 81.8% are insectivores, and 14.5% are omnivores. In contrast, 58.2% of the 55 species are resident insectivores that live in small groups, 10.9% are resident omnivores that live in small groups, and 12.7% include subspecies that are resident insectivores. We used these combinations of traits of known cooperative breeders and phylogenetic relationships to infer that an additional 106 species of songbirds in China are probable cooperative breeders and 22 species are possible cooperative breeders. Our analysis suggests that a maximum of 27.2% (183 of 674 species) of Chinese passerines are cooperative breeders, with more occurring in subtropical southern China than in temperate northern China. Cooperative breeding is the main breeding system of species in the families Corvidae, Pycnonotidae, and, especially, Timaliidae (105 of 183 species, 57%). Based on our analyses, cooperative breeding might be more common than previously assumed, particularly among species in the families Timaliidae, Corvidae, and Sturnidae, and species in southern, subtropical China. Because most cooperative-breeding species in our study were either inferred cooperative breeders or possible cooperative breeders, additional study of these species is needed to confirm our results. Abetter understanding of the prevalence of cooperative breeding in birds will improve our insight into the evolutionary and ecological factors that select for cooperative breeding.