Urbanization alters fear behavior in black-capped chickadees

Urban landscapes contain a multitude of novel sensory stimuli, and urban dwelling animals, such as songbirds living near human dwellings, must quickly learn how to respond to these unfamiliar cues. When exposure reveals that a stimulus is associated with a cost, fearful behavior should increase. Conversely, neophobic fear should decrease when negative outcomes do not regularly follow the stimulus. Because exposure to anthropogenic stimuli is more common in birds that inhabit urbanized landscapes, their fear response patterns should more accurately reflect the risks associated with these stimuli. We conducted a series of feeder and playback experiments to explore whether urbanization altered black-capped chickadees’ (Poecile atricapillus) fear responses to model cats, humans, a novel object, and anthropogenic noise. We predicted that fearful responses to cat models would increase in birds as urbanization increased because negative interactions with cats are more common in the city. However, we expected urban birds to be less fearful of our other stimuli because fitness costs are absent or less severe. As predicted, the fear of cats increased with urbanization, but the fear of noise decreased - as indicated by willingness to visit a feeding station. Other stimuli were not associated with urbanization, which may be related to the use of county and city parks where human presence is relatively common. Nonetheless, our results suggest that plastic fear responses to novel stimuli may facilitate urban success in the black-capped chickadee. More generally, behavioral plasticity may indicate the ability of a species to thrive in the urban environment.