Evidence of carrion consumption behaviour in the long-eared owl Asio otus (Linnaeus, 1758) (Aves: Strigiformes: Strigidae)

Abstract

Evidence of necrophagous behaviour has been reported for 8.43% of nocturnal raptors. To determine whether preys were captured alive or consumed as carrion is challenging, as the diet of Strigiformes is mainly studied through pellet analysis, rather than direct observation. The diet of the long-eared owl Asio otus has been widely studied all over the distribution range of this species, but proven evidence of this feeding habit is still lacking. We collected 106 pellets under a suburban dormitory in Southern Tuscany (Central Italy) between December 2012 and April 2013. Prey remains (skulls, mandibles) were compared with a specific atlas. Four fragments of crested porcupine (Hystrix cristata) quills and a jawbone of Martes sp. were found in pellets collected after a snowfall (20–40 cm in depth). Although voles and mice constituted the staple of the diet of this species, accordingly with previous studies, these findings represent the first proof of carrion consumption by the long-eared owl. Body sizes of crested porcupine and Martes sp,, as well as the defence behaviour of the rodent, rule out a direct predation by the owl. Our study enlarges the trophic spectrum of the long-eared owl, thus adding a further dimension to the behavioural plasticity of this species.