Carnivore communities are diverse and complex, and for conservation strategies to be effective conservationists must understand the magnitude and direction of intraguild interactions ranging from predation to niche partitioning. To determine how intraguild interactions affect spatiotemporal distributions of carnivore communities in the Apostle Islands, we studied carnivore populations using camera traps from 2014-2018. We used generalized linear mixed-effects models to test whether the subordinate carnivore presence in conspecific pairings was related to dominant carnivore relative abundance or island biogeography at two different spatial scales (island-level and camera site-level). To determine whether subordinate carnivores were using temporal partitioning, we calculated temporal overlap between each pair of subordinate and dominant species. At the island-level, island biogeography variables were included in top models for presence of all subordinate species, except for fisher, while relative abundance of a dominant carnivore was in the top models for presence of all subordinate species, except for grey fox. At the site-level, relative abundance of dominant carnivores was not a significant predictor of subordinate carnivore presence. Additionally, all pairs exhibited high or neutral temporal overlap. Findings indicate that island biogeography and competition are both important factors structuring the spatial distribution of the carnivore communities in the archipelago. Different drivers between scales highlights the importance of scale in structuring communities. Despite the minimal evidence for spatial or temporal partitioning within the carnivore community on the Apostle Islands, subordinate carnivores could be partitioning at a finer scale than we were able to measure, further highlighting the need to measure niche partitioning at multiple scales.
Understanding anthropogenic impacts on wildlife is necessary for effective conservation of wildlife species. While protected areas are often considered strongholds for wildlife populations, recent research in protected areas has highlighted that both human activity and footprint can be detrimental to wildlife. To determine how human activity (presence) and footprint (structures) affect the spatiotemporal activity of the carnivore community on the Apostle Islands National Lakeshore, we monitored the carnivore community for five years (2014-2018) using camera traps. When tested year-round, we found all structure types had a negative impact on carnivore community relative abundance, except for campgrounds, which were positively related to carnivore community relative abundance. Responses of individual carnivore species to anthropogenic structures varied depending on structure type. When replicating the same models for the seasons when park visitation is common, we found differences between the seasonal and aseasonal models, suggesting that human presence does change the effects on the carnivore community. We also compared carnivore nocturnality along a gradient of anthropogenic activity, but our results indicate that the carnivore community did not become more nocturnal with increasing anthropogenic activity as we expected. Despite no displayed increase in nocturnality in response to human activity, the carnivore community did display spatial avoidance of current, historical, and private anthropogenic structures, which increased in the season that visitors were more prevalent. Our study indicates that human footprint potentially reduces the effectiveness of protected areas.
Funding and Partners
- National Park Service
- Northland College
- GLNF CESU Agreement through the Apostle Islands National Lakeshore
- Sigurd Olson Professorship in the Natural Sciences and Morris O. Ristvedt Professorship in the Natural Sciences through the Department of Natural Resources at Northland College
- Schorger Fund and Beers-Bascom Professorship in Conservation through the Department of Forestry and Wildlife Ecology at the University of Wisconsin – Madison
- NASA Earth and Space Science Fellowship