The impact of vegetation characteristics and prey availability on breeding habitat use and diet of Little Owls Athene noctua in Central European farmland

Capsule Foraging habitats are determined by vegetation characteristics rather than the availability of insect prey.

Aims To determine the diet composition of Little Owls in relation to the availability of insects at foraging sites, and to elucidate the main factors determining the owls’ habitat choice.

Methods The feeding ecology of Little Owls was studied during the 2002 breeding season in the agricultural landscape of western Bohemia (Czech Republic), where its population is in decline. Diet composition was determined by pellet analysis. Insect availability was studied using pitfall traps in the two most important Little Owl foraging habitats. For both habitats, we assessed the main vegetative characteristics (average and maximum vegetation height, vegetation density).

Results Based on number, insects were the most dominant prey, followed by small mammals; based on weight, insects comprised only a minor part of the diet. Among insect prey, Carabidae beetles were the most abundant. The proportion of insect numbers was strongly positively correlated with advancing day of the season and negatively correlated with the proportion of vertebrates. Although the highest densities of Carabidae were found in cornfields Little Owls significantly preferred grassland habitats, probably because of the lower vegetation cover.

Conclusions The availability of short sward vegetation in grassland habitats during the breeding season may play a key role in the conservation of Little Owls in central European farmland.