Bobcat occupancy on tree islands diminished by invasive Burmese pythons in an Everglades conservation area (R-Scripts and raw data)

Bobcats (Lynx rufus) are terrestrial mammals that also inhabit tree islands embedded in the Everglades wetlands, which serve as the upland refuge habitat during the wet season. The Everglades is heavily managed, and little is known about how water levels or other landscape-level factors may influence bobcat occurrence on tree islands in this wetland ecosystem. We used game camera records and occupancy modeling to test for effects of static habitat variables, dynamic hydrologic variables, and hypothesized that deep water levels would reduce bobcat occupancy on tree islands. We also tested for the effects of an expanding invasive snake, the Burmese python (Python molarus bivittatus) using output from a model constructed to predict density and spread of Burmese pythons across southern Florida. We built detection histories using 1,855 bobcat images from game cameras set on 87 tree islands in an Everglades conservation area from 2005-2019 and tested hypotheses about bobcat use of tree islands relative to landscape covariates, hydrologic covariates, and predicted spatiotemporal Burmese python densities. The results of our occupancy models indicated that bobcat occupancy was significantly diminished when predicted Burmese python densities exceeded ~3 pythons/km2. We also found bobcat occupancy probability increased steadily with tree island density around the focal tree island. Additionally, relative water depths surrounding tree islands did not appear to influence bobcat occupancy. Our results provide evidence that the conservation of tree islands (especially clusters of tree islands) and management of invasive Burmese pythons may influence bobcat occupancy in the Everglades more significantly than hydrologic factors.