Frequency of Occurrence and Ingested Biomass of Different Prey of the Barn Owl Tyto alba in an Island Ecosystem

Pellets of the Barn Owl have been widely used to assess small mammal assembly in several ecosystems, and their analysis is particularly important for Mediterranean islands, where a low assembly of species may occur with respect to the mainland. In this work, we assessed the diet of the Barn Owl in Elba island (Central Italy) 30 years after the first study on this species in the same study area, through pellet analysis. Small mammals built up the staple of the diet of this raptor bird on the island, with birds being the second prey category. The presence of a skull of the Geoffroy's Myotis Myotis emarginatus confirmed the presence of this species on the island after over 60 years from the first and still unique record of the Tuscan Archipelago. Moreover, fragments of two newborn hares were detected, increasing the knowledge on the local trophic spectrum of the Barn Owl. The Barn Owl Tyto alba is commonly reported as a non-selective predator of small mammals, and its diet has been thoroughly analyzed also to assess the small mammal assembly composition in many study areas. The aim of this work was to analyze the diet of the Barn Owl in the Elba island through the analysis of 161 pellets collected in September 2020. Undigested fragments were isolated and compared with reference collections. We confirmed that the Barn Owl is a typical predator of field mice (62% of relative frequency), with synanthropic murid rodents as the second category of prey. The frequency of consumption of shrews increased by 9% with respect to the previous work, suggesting that the natural environment of Elba island is still in a good health status. Moreover, fragments of two newborn hares were detected, increasing the knowledge on the local trophic spectrum of the Barn Owl. Finally, the skull of a Geoffroy's Myotis Myotis emarginatus confirmed the presence of this species in Elba island after over 60 years from the first unconfirmed record. Repeated studies conducted in the same study site may provide useful information on prey population trends and local environmental status.