Effects of protected areas on human‐induced shifts in nocturnal activity in mammal communities in southwestern China

Human activities have extensive influences on wildlife communities through lethal and sublethal effects. Protected areas (PAs) can reduce lethal impacts of humans on wildlife by reducing direct killing of animals, but whether PAs can help mitigate sublethal impacts on animal behaviors, such as the human-induced shifts toward nocturnal activity (hereafter nocturnal shifts), remains unclear. Using extensive camera-trap data from 21 study sites encompassing 1897 camera locations inside and outside PAs across a global biodiversity hotspot, the Mountains of Southwest China, we examined the differences in nocturnal activities of 29 mammal species under varying values of the human modification index (HMI) inside and outside PAs at community and guild levels. At the community level, the shift to nocturnal activities as HMI increased was more pronounced inside than outside PAs (p > 0.95). Except for the diurnal and carnivore guilds, most guilds delayed significantly their activity time as HMI increased outside PAs (86-100% probability density [PD] > 0). Delays in different guilds ranged from 1.23 to 2.89 h as HMI increased from 0 to 0.35. Inside PAs, only omnivores showed a significant delay (84% PD > 0). These findings provide behavioral evidence that PAs provide temporal refuge for mammals by reducing human impacts on their diel rhythms, revealing an important mechanism by which PAs contribute to wildlife conservation through their mitigation of sublethal human impacts.