Fieldfare nestlings and fledglings feeding and adoption by the European Blackbird

Inter-specific adoption is an intriguing topic in behavioural and evolutionary ecology. Being a rare phenomenon is rarely documented in the literature and thus reports of inter-specific adoption based on solid data are particularly valuable. Here, owing to a long-term and extensive monitoring of a local population of the European blackbird (Turdus merula, hereafter blackbird), we describe observations of alloparental behaviour exhibited by blackbirds towards fieldfare (Turdus pilaris) nestlings (single nest, first record ever) and fledglings (twelve cases in total). We discuss the observations in respect to available literature.