Adoption of nestlings by foster parents in captivity (Cade 1980, Granthon et al. 2021) and in the wild (González et al. 1986, Pande et al. 2004) has been found to be better than hand-rearing young in captivity to promote their fledging success (Hahn and Yosef 2020) and subsequent recruitment into the breeding population (Collopy 1986, Constantini et al. 2009). Although inter-specific cross-fostering and intra-specific fostering have been tested as a raptor management technique for several decades (e.g., Meyburg 1977, Bird et al. 1985), the species in which potential foster parents will accept unrelated nestlings into their broods remains uncertain. (Following Bird et al. [1985], we use the term “fostering” exclusively for intraspecific adoption.)
Most reports of fostering of diurnal raptors involve eagles (Aquila pomarina [Meyburg 1977], A. chrysaetos [Collopy 1986], A....
