Interspecific Feeding in Birds: A Short Overview

Interspecific feeding is an uncommon behaviour where an individual of one species feeds individuals (mostly offspring) of another species. Observations have been made in many avian species but causes of this behaviour remain unknown and no hypothesis was proposed to fully explain its occurrence. In this review, I collected observations of interspecific feeding in birds reported during the last 40 years and compiled a comprehensive dataset based on all published reports of interspecific feeding. It consists of 186 cases observed in 107 species worldwide and summarizes the information on involved species, their age, sex, and possible causes of this misdirected parental care. Additionally, I report a case of Great Spotted Woodpeckers' Dendrocopos major young fed by Eurasian Nuthatches Sitta europaea. Observations of interspecific feeding are highly skewed in favour of North American and European species, probably due to historical (long research and ornithology traditions) and language issues (publishing in English). Interspecific feeding does not seem to be related to nest type but is mostly associated with males allured by loud calls of nestlings from nearby allospecific nests. However, most of the observations remain only anecdotic and an empirical research that would try to find plausible explanations of the evolutionary advantages of this behaviour still remains to be carried out.