Fledgling adoption in European Blackbirds: an unrecognized phenomenon in a well-known species

Abstract

Fledgling adoption in passerines is a poorly known phenomenon. Our long-term study of blackbirds has indicated that adoption could ensue from an error on the part of parent birds in recognizing their own progeny or an intergenerational conflict won as a result of the effective begging behavior of fledglings directed at adult blackbirds other than their parents. Our findings did not show that the Blackbirds in our population actively kidnapped fledglings younger than their own offspring.