Proximity to human settlements can reduce vigilance, but increase alarm call responses in African antelopes

Human activities can have complex effects on the antipredator behaviour of wildlife, and an under-standing of the intricacies can provide important information for conservation management. In some cases, 'human shields' that attract wild ungulates may form around human settlements due to a lower density of large predators. However, human presence may also be associated with increased exposure to a range of anthropogenic threats, such as poaching, predation by dogs and costly interactions with livestock and their herders. Here we compared the antipredator behaviour of two savannah antelopes, topi, Damaliscus lunatus, and Thomson's gazelle, Eudorcas thomsonii, between the relatively undisturbed areas in the interior of the Maasai Mara National Reserve (Kenya) and the peripheral areas next to human settlements by the reserve boundary. We found that both antelope species were less vigilant in the more human-impacted peripheral areas, suggesting a reduction in the overall predation risk. However, both species also responded more strongly to conspecific (but not heterospecific) alarm calls in the human -impacted areas. We suggest that alarm calls in the human-impacted areas may be elicited by a more variable and unpredictable set of threats, many of which are anthropogenic, and that these require more careful assessment by the antelopes. Human presence can thus have opposite effects on different aspects of antipredator behaviour, emphasizing the need to better understand how animals perceive threats in their environment and the consequences for population performance.(c) 2023 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.