Many avian species rear or help rear offspring that are not their own. Although many hypotheses have been invoked to explain such behavior, these alternative explanations continue to enjoy a lively debate (e.g., Park 2007, Nowak et al. 2010, Abbot et al. 2011). Here, I report from Hokkaidō, Japan, an example of yet another species, the Blakiston's Fish Owl (also known as Blakiston's Eagle-Owl; Bubo blakistoni), in which a male helped rear offspring that were not his. In addition, I present an example of a paired wild male performing courtship behaviors with a second female, which was in captivity and housed with a captive male. Their interactions included attempted courtship feeding and duet vocalizations. I discuss two potential explanations for these behaviors.
Blakiston's Fish Owls are the largest owls in the world and endemic to northeastern Asia (Hokkaidō, Japan [Takenaka 2018], the Russian Far...