干旱区生态环境知识资源中心

Intraguild predation (IGP) by a dominant predator can drive the spatial dynamics of a subordinate predator and may explain space-use patterns that deviate from theoretical predictions that species will use areas that maximize the availability of limited resources (resource availability hypothesis). Intraguild predation may suppress the distribution and abundance of mesopredators, but spatial resource partitioning may facilitate coexistence, with the subordinate carnivore utilizing suboptimal habitats. In arid systems, free-standing water was historically scarce, limiting the distribution of larger-bodied predators and offering large areas of refugia for smaller, arid-adapted species, such as the kit fox (Vulpes macrotis). In these systems, the development of artificial water sources may facilitate an increase in the distribution and abundance of larger carnivores (e.g., coyotes [Canis latrans]), perhaps to the detriment of kit foxes. We coupled noninvasive genetic sampling and dynamic occupancy models to evaluate the spatial dynamics of kit foxes and their intraguild predators, coyotes, in western Utah, United States. We evaluated the influence of habitat characteristics on coyote occupancy patterns, and then investigated the role of habitat and coyotes on kit fox space use at multiple scales. Coyote occupancy was unrelated to water availability, but was positively related to the proportion of shrubland and woodland cover, a pattern consistent with predictions of the resource availability hypothesis. Supporting predictions of IGP theory, kit fox occupancy was negatively related to shrubland and woodland cover, minimizing overlap with land-cover types favoring coyote occupancy. Furthermore, kit fox probability of local extinction was positively related to coyote activity. Interestingly, kit fox detection was positively related to coyote activity (i.e., kit fox detection was higher on spatial surveys with greater coyote sign), suggesting that at finer scales, kit foxes utilized riskier habitats to secure sufficient resources. Our results identified two alternative states predicted by IGP theory (i.e., intraguild predator dominated and coexistence of intraguild predator and intraguild prey) in a single system and elucidated the importance of considering dynamic processes and scale when investigating IGP.