Keep Calm And Carry On: Reactive Indifference To Predator Encounters By A Gregarious Prey Species

Strategies that mitigate predation, whether proactive or reactive, can nevertheless impose significant 'nonconsumptive' costs on prey species. Here we used data from two wild vervet monkey, Chlorocebus pygerythru,s groups to assess whether the detection of predators affected their subsequent behaviour to the detriment of their short-term foraging effort. Encounters with the three predator classes present at our study site were frequent and there was evidence that animals were more likely to shift to predatorfocused vigilance, which was modulated by alarm call intensity, but not predator type, in the hour following detection. Nevertheless, and against expectation, there was no detectable shift in overall levels of vigilance, which remained low, interindividual distances, travel bearing and, consequently, effort put into foraging. We consider this surprising imperturbability by our study groups in the context of population group size, as our groups are large and have correspondingly lower levels of individual vigilance, as well as in terms of the constraints imposed by small, overlapping territories and frequent predator encounters. Finally, we advocate for increased consideration of the responses of the predators themselves to detection by their prey. (c) 2021 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.