The diet of the burrowing owl in open habitats of southern Brazil

Abstract

Athene cunicularia’s diet is composed of vertebrates and invertebrates, whose relative frequencies can change in space or time. We analyse habitat and temporal variation in the weight and the composition of prey in bird pellets. We collected 396 pellets from nine owl couples for six months and in three open habitats: near forest, far from forest, and urban. Mean pellet weight was 1.03 g. August showed pellets 15% heavier and March 22% lighter than average, differing from the other months. Regarding composition of prey, vertebrates occurred more in the pellets during June, July and August, while invertebrates showed higher frequency in summer months in open habitats far from forest. At the lower taxonomic level, we identified the presence of mammals, serpents, amphibians, birds, beetles, ants, spiders, grasshoppers, woodlice, molluscs and cockroaches in the pellets. The diet during winter in open habitats far from forest showed higher presence of mammals, while summer months in open habitats near forest and in urban habitats showed more hymenopterans. The results showed that A. cunicularia preys on a wide spectrum of prey, but we found some preference for specific prey depending on the season and on the open habitat types.

Keywords: Atlantic Forest, pellets, spatial effect, time effect.