False mating of Blackbird (Turdus merula) and Fieldfare (Turdus pilaris)

During an intensive study of the urban population of the Blackbird Turdus merula in Szczecin (1997-2023), four cases of surrogate copulation were observed in the Blackbird and three in the Fieldfare Turdus pilaris. In three cases birds (Blackbirds twice and Fieldfare once) try to copulate with fledglings of their own species, in all other cases the birds try to copulate with moss and sticks. In three cases copulation attempts were done by adult birds (two blackbirds and one fieldfare), in four cases it was a fledgling.