Effects of human approach directness and path use on small mammal risk perception

Abstract

Prey effectively avoid predation by dynamically assessing their risk and responding accordingly. Various aspects of the predator’s approach (e.g., eye contact, approach directness, speed, path presence, etc.) can strongly influence prey risk perception and choice of antipredator strategy. The following study investigates how desert cottontails, Sylvilagus audubonii, eastern fox squirrels, Sciurus niger, and California ground squirrels, Otospermophilus beecheyi perceive risk posed by human approaches that vary in both path presence (on-path versus off-path) and directness of the approach. For squirrels, on-path approaches led to shorter flight initiation distances (FIDs) when compared to off-path approaches, and more direct approaches led to shorter FIDs, contrary to our predictions. For cottontails, on-path approaches decreased their probability of taking flight when compared to off-path trials. In addition, more direct approaches increased cottontail probability of flight, but for those that fled, more direct approaches led to shorter FIDs, like squirrels. We did not find evidence of an interaction between approach directness and path presence for cottontails or squirrels. Altogether, these results may suggest cottontails utilize a switch between multiple predator avoidance strategies (i.e., fleeing early before predator detection vs. relying on crypsis and fleeing late) when presented with different contexts of human approach.