Bat predation by long-eared Owls in mediterranean and temeperate regions of southern Europe

Abstract

.--Wdee scribeds patial and temporal variation in bat consumptionb y Long-earedO wls (Asio otus) at a coastal site of eastern Spain and examined the importance of bats in the diet of this raptor in nine temperate and 21 Mediterranean localities of southern Europe. In our study site in Spain, bats accountedf or 2% of prey items,w hich is the largestp ercentages o far reported for the speciesT. he vast majority of bats were Pipistrellussp p. Bat predation occurred in all seasonsb, ut was significantly higher in spring and summer. The temporal pattern of bat predafion was unrelated to temporal variation in the consumption of rodents, the dominant prey in the diet. Although a consistent increase in bat intake only in years of rodent scarcity predicts an aggregation of occurrences over time, bat occurrence during 31 successivsee asonsw asn ot different from a random sequence.P elletsc ontainingb at remains originated mainly from one communal roosting site. Bat remains appeared in pellets from five of 16 nests, accounting for 17% of prey items on average. In southern Europe, bats occurred in 38% of diets in the Mediterranean region, while they were absent in diets from adjacent temperate localities. Our results suggest that Long-eared Owls prey on bats rarely and opportunistically in Mediterranean sites, but also that bat aggregationsc ould be a locallyi mportant food sourcef or somei ndividual owls during certain periods.