Short-term social dynamics following anthropogenic and natural disturbances in a free-living mammal

Abstract

Anthropogenic disturbances are widely recognized for their far-reaching consequences on the survival and reproduction of wildlife, but we understand comparatively little about their effects on the social lives of group-living animals. Here we examined these short-term changes in affiliative behavior as part of a long-term study on a human-tolerant and socially flexible population of California ground squirrels (Otospermophilus beecheyi). We used social network analysis to examine short-term changes in affiliative behavior and individual consistency in response to disturbances by humans, domestic dogs, or a natural predator (the coyote). Overall, juveniles were more involved than adults in affiliative interactions, but the short-term directional effects of these acute disturbances on social cohesion varied by disturbance type. Human and dog presence reduced aboveground connectivity, particularly for juveniles, whereas disturbances by coyotes generally promoted it. Beyond these effects, we also detected non-random responses to disturbances, though individuals were not very consistent in their directional response to different disturbance types. Our results demonstrate the flexible changes in social behavior triggered by short-term disturbances imposed by humans and other threats. More generally, our findings elucidate the underappreciated sensitivity of animal social interactions to short-term ecological disturbances, raising key questions about their consequences on the social lives of animals.

Sensory integration of danger and safety cues may explain the fear of a quiet coyote

“…B 290: 20231812 those residing at the relatively pristine site [69,77]. Moreover, ground squirrels at our study sites have consistent individual differences in behaviour across time and contexts [36,63,75,78].…”

“…Another major finding of our study was that individuals were consistent in their behavioural reactivity—but not in their time spent near stimuli—across treatments. This finding adds to our growing understanding of the consistent individual differences in California ground squirrels [36,63,75,78] and other animals [76,110,111]. More broadly, given that individuals residing at the human-impacted site were also consistently most reactive to predator cues, future studies should investigate the extent to which fear of predators generalizes to fearfulness of other dangers, including humans [112].…”

“…Animals at the disturbed site are generally less reactive to humans, have higher glucocorticoid levels, and are in poorer body condition than those residing at the relatively pristine site [69,77]. Moreover, ground squirrels at our study sites have consistent individual differences in behaviour across time and contexts [36,63,75,78].…”

“…Second, we investigated the extent to which individuals experiencing divergent levels of human and dog activity differed in their responses to the predator cues. At our disturbed site, domestic dogs directly kill, chase and disturb squirrels whereas dogs rarely visit the relatively pristine site [63] (see Methods for details). Because mammalian prey often respond similarly to odours from domestic dogs and wild canids [64,65], we expected squirrels at the disturbed site to be more reactive to coyote cues than those residing at the pristine site (i.e.…”

Otospermophilus douglasii (Rodentia: Sciuridae)

“…It is also worth noting that recent studies in Alameda County on O. beecheyi documented complex social networks (Smith et al 2018) and reduced vigilance during foraging as group sizes increased (Ortiz et al 2019). Moreover, it will be interesting to learn how human presence influences O. douglasii ; humans and their dogs disrupt the foraging behavior (Ortiz-Jimenez et al 2022) and social cohesion (Gall et al 2022) of foraging O. beecheyi , imposing physiological consequences for individuals (Hammond et al 2019) that likely influence gut microbial diversity (Person et al 2023). These responses are importantat least for O. beecheyi because squirrels with high levels of stress hormones, measured as fecal glucocorticoid metabolites, are less resistant to rattlesnake venom (Holding et al 2021).…”