Experience affects novel object aversion and the use of human cues in rural and urban American crows

Abstract

Population differences in behavior can result from experience, which can be drastically different between environments such as urban and rural areas. Urban areas may be more complex, contain more human-made objects but fewer natural objects, or have more non-threatening people. Consequently, animals in urban and rural populations may differ in neophobia levels, what is novel, and attention to human behavior. We conducted two experiments with a common urban bird, the American crow (Corvus brachyrhynchos). On home territories of urban and rural crow family groups, we presented objects that were either equally novel in both environments or more common in one environment than the other. Separately, we measured flight initiation distance (FID) from an approaching person using either a direct or averted, less threatening gaze for individual crows across an urban gradient. We found that urban crows were more neophobic than rural crows, as measured by the probability of feeding near an object that is equally novel in both environments. There were no differences in approach and feeding latencies for the least neophobic family member. Both urban and rural crows were less averse to objects that were more common in their respective environments. In the FID experiment, crows in highly urbanized areas had FIDs 25 m shorter for an indirect gaze, while rural crow FIDs were unaffected by gaze. FIDs were best predicted by crows’ experiences with people in a relatively large area around each trial. These results highlight how experience must be accounted for when considering population differences in behavior.