First data on the short-eared owl (Asio flammeus) prey in Patagonia (Argentina)

Abstract

The short-eared owl (Asio flammeus) has a wide distribution across the world, and it inhabits open lands, grasslands, and marshes. Small mammals are its main prey, but it also feeds on other food items according to seasonal variations. Despite its wide distribution, little information about its food habits has been published in Argentina and none for Patagonia. In this study, we report the analysis of nine pellets of this species for a site located 6 km north of Puerto Madryn city (Chubut, Argentina). This area is located in the Monte Phytogeographical Province and has a flooded place with sewage water, invasive weeds, and herbaceous vegetation. We measured pellets and disaggregated them using hot water; all prey remains were identified to the finest taxonomic level. We found 49 prey items: 73.5% of small mammals (mainly native rodents and marsupials) and 26.5% of insects (mainly spider wasps); small mammals were the prey that contributed the most to biomass (99.2%). Our results are consistent with previous works carried on the southern distribution of this species, where rodents were the most consumed prey and the main item to biomass. However, we found the lowest percentage for rodents in comparison with other studies in southern South America. We did not record birds among prey, although this item was found in previous studies. Despite we analyzed a small sample, this study is the first contribution for Argentinean Patagonia on the diet of A. flammeus, a species with a wide geographic distribution that lacked of food habits data in this region.