Spatiotemporal overlap of sympatric mesocarnivores in central British Columbia, Canada

,Many wildlife species use similar resources, leading to the potential for overlapping niches. These overlaps can create negative interspecific interactions, including different forms of competition. Niche overlap can be experienced on several different axes, including spatial, temporal, and dietary. There are many factors that may affect species co-occurrence patterns, including population cycles, natural and anthropogenic landscape change, harvest mortality, and changes in resource availability. Effective wildlife management is dependent on an understanding of the interaction between community dynamics and competition. Many mesocarnivores in central British Columbia overlap spatially, temporally, and dietarily. This high degree of overlap means that understanding the mechanisms facilitating their coexistence is particularly important. I used five years of data from remote cameras and fine-scale habitat data from LiDAR to assess patterns in the spatial and temporal co-occurrence of short-tailed weasels (Mustela erminea), American mink (Neogale vison), American marten (Martes americana), fishers (Pekannia pennanti), wolverines (Gulo gulo), and Canada lynx (Lynx canadensis). During this study, there were fluctuations in snowshoe hare (Lepus americanus) abundance, as well as many predators, specifically decreases in lynx and increases in fisher. Habitat features, like structural complexity, can facilitate species co-occurrence by allowing for fine-scale niche partitioning. I used multi-species occupancy models to test hypotheses about the relationships between mesocarnivore co-occurrence and habitat. Mesocarnivores were more likely to co-occur at sites with greater complexity of vertical forest structure and at sites closer to riparian zones. Short-tailed weasels, however, did not co-occur with other mustelids in riparian zones. Importantly, I found that habitat covariates associated with co-occurrence were relatively similar over time despite notable changes in the abundance of predators and prey. My findings highlight the importance of riparian habitats and forest complexity in facilitating species co-occurrence in harvested forests. Temporal niche partitioning is a second mechanism that allows species to co-exist in space and may occur if one species shifts its temporal activity patterns to avoid interactions with another. I tested the hypothesis that smaller-bodied species would shift their activity in the presence of larger-bodied species. I found partial support for this hypothesis in that marten activity differed in the presence of larger-bodied lynx when lynx were abundant but not when lynx were rare. Furthermore, the activity patterns of the largest mesocarnivores in our study, lynx and wolverine, were unaffected by the presence of smaller species. In contrast with my hypothesis, weasel activity was similar in the presence of larger-bodied species. Collectively, these findings suggest that mesocarnivores may alter their temporal use of habitat to avoid co-occurrence in response to the presence of other species. Combined, my research provides insight into the mechanisms by which mesocarnivores—species with overlap in diet and habitat—share space. My findings highlight the importance of forest management practices that retain structural complexity and riparian areas to promote the co-existence of sympatric mesocarnivores. Further, my results emphasize the responses of sympatric species to changes in community dynamics, which is important for understanding the effects of population cycles on species co-occurrence.

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