Influence of captive breeding, release date and sex on the natal philopatry of the lesser kestrel Falco naumanni

The lesser kestrel Falco naumanni is a facultative colonial falconiform whose breeding range stretches across the entire Palaearctic. As with other pseudo-steppe birds, the lesser kestrel has experienced a sharp decline in western Europe over the last decades, spurring conservation actions. We compared natal philopatry of captive versus wild-bred individuals and the effect of release date on philopatry by comparing return data of captive- and wild-bred kestrels from 13 colonies between 2004 and 2019. We found that wild-bred kestrels show significantly stronger philopatry than their captive-bred counterparts, possibly due to the lack of parental influence experienced by the latter during their first days. No relationship was detected between release date and natal philopatry. Future studies should focus on factors affecting the philopatric behaviour of lesser kestrels bred in captivity, which could in turn improve their captive breeding and release strategy.