Differential defensive response of common kestrels against a known or unknown predator

Abstract

We studied the nest defence behaviour of common kestrel (Falco tinnunculus) pairs against a mount of either a known predator (the hooded crow, Corvus corone cornix) or a novel predator (the raven, Corvus corax). Both corvids are nest predators, are very similar in shape, but the raven is unknown to kestrels living in the study area. This study aimed to ascertain the existence of possible nest defence behaviour variation in relation to familiarity or novelty of the predator. The crow, the known predator, was attacked more often than the raven, the unknown predator. Males and females, considered separately, displayed a similar response against both predators, but females attacked the crow more vigorously than males. Regardless of predator type, the behaviour patterns indicating higher defensive motivation were performed similarly by both partners and some difference arose only in those indicating a moderate defensive motivation. We conclude that predator recognition is likely learned in this species and that knowledge induces the larger partner, the female, to defend the nest more strongly than the male.