Adoption and feeding of fieldfare nestlings and fledglings by European blackbird.

Interspecific adoption is an intriguing topic in behavioral and evolutionary ecology. As it is a rare phenomenon, seldom documented in the literature, reports of interspecific adoption based on solid data are particularly valuable. A long-term and extensive monitoring programme involving a local population of European blackbirds ( Turdus merula , hereafter blackbird) has yielded, among other things, observations of alloparental behavior exhibited by blackbirds toward fieldfare ( Turdus pilaris ) nestlings (a single nest, the first-ever record) and fledglings (12 cases in all). We discuss the observations in the context of the available literature.