Some factors influencing mobbing behavior in Barn Swallows ( Hirundo rustica)

Abstract

Mobbing responses were greater toward a taxidermic model of a Great Horned Owl than toward a model of a male Wood Duck or toward other artificial stimuli. Manipulating various anatomical parts of the models disclosed that mobbing was greater toward models with the owl head, beak, and/or eyes than toward models without these features. Mobbing was greater when stimuli were presented near the colony than when presented further away, but the swallows exhibited rapid habituation to models regardless of type of model or distance of presentation. Mobbing responses were more frequent when the first group of young were present than during pre- or postnesting phases, when eggs were present, or when the second group of young were present. These results suggest that recognition of avian predators by Barn Swallows is by key features of the predator and that responsiveness of the swallows depends on a balance between their reproductive phase and the proximity and behavior of the intruder vs the time and energy cost of sustained mobbing.