Habitat and Interspecific Interactions Affect Mesocarnivore Occupancy in the Eastern U.S.

Michael Egan, Purdue University

Abstract

Interspecific competition is important to carnivore communities because of the propensity of carnivores toward aggressive interactions. Interactions among members of the eastern U.S.A. mesocarnivore community have been impacted by the loss of top predators and urbanization. Changes to interspecific interactions and habitat result in changes in many populations of mesocarnivores. Interactions between these two factors further explain contrasting patterns among the members of the mesocarnivore community. These patterns have been studied at scales from the effects of microhabitat to landscape scale factors on mesocarnivore occupancy, however they have not been studied throughout multiple independent landscapes in the eastern U.S.A. Here, we used presence absence data from camera traps across the eastern U.S.A. to test the effects of habitat and interspecific interactions on members of the mesocarnivore community. We used single- and two-species occupancy models to estimate the contribution of urbanization and competition with coyotes to declines in gray fox populations. We found that increasing coyote abundance was negatively related to gray fox occupancy, but gray foxes did not respond to urban features. Additionally, we used multi-species occupancy models to investigate the effect of habitat on interspecific interactions among five mesocarnivores. We found that increased urbanization reduced the strength of potential intraguild predation on some mesocarnivores. Collectively, our results suggest that neither interspecific interactions nor habitat alone are capable of explaining patterns in the mesocarnivore guild. However, the inability of mesocarnivores to avoid competition with intraguild predators may contribute to declines in some species. While urbanization may have direct negative impacts, urban areas may be important because of reduced competition in more urbanized landscapes. Given the continued urbanization of the eastern U.S.A., these data provide valuable insight into how habitat may impact interspecific interactions, and, ultimately, how interspecific interactions may affect mesocarnivore occupancy.

Degree

M.S.

Advisors

Zollner, Purdue University.

Subject Area

Ecology|Zoology

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