Intraspecific Adoption and Double Nest Switching in Peregrine Falcons (<i>Falco peregrinus</i>)
We describe an observation of post-fledging double nest switching and alloparenting in the Peregrine Falcon (Falco peregrinus tundrius). During the summer of 2010, a 36-day-old male Peregrine Falcon that had been marked with leg bands was seen flying from its natal site and was subsequently observed at a neighboring nest site that contained two nestlings. Motion-sensitive camera images indicated that the adopted nestling remained at the neighboring site for several days, during which time it shared the nest ledge with the two resident nestlings and was fed by the adults that occupied the site. The juvenile falcon subsequently returned to its natal site, where it shared the nest ledge with its natural sibling and received care from its natural parents. This note is the first documentation of nest switching in wild Peregrine Falcons.