Abstract
The Eastern Indigo Snake (Drymarchon couperi) is a large, non-venomous snake endemic to the southeastern Coastal Plains of the United States. Due to habitat loss, fragmentation, and collection for the pet trade, this species is listed as federally threatened under the Endangered Species Act. Several studies have looked at D. couperi movement and life history throughout the central and northern portions of their range, but we lack ecological information in regards to the southernmost populations. South Florida differs drastically in climate and habitat features from more northern parts of the state and may require varying management approaches for D. couperi conservation. The present research uses radio telemetry to study D. couperi home range sizes, seasonal variations, habitat and refugia utilization, detectability patterns, and general behavior. The study took place at Rookery Bay National Estuarine Research Reserve along the Gulf coast of southwest Florida. The Reserve comprises a myriad of habitats including mangrove swamps, upland pine hammocks, and coastal scrubland. Rookery Bay Reserve is a protected area with minimal anthropogenic disturbances; however, it is bordered by growing development. Four snakes (one female and three males) were tracked between August 2015 and April 2017. Home ranges varied from 113 – 233 hectares. There were no significant differences in home range size between the breeding/dry season and the non-breeding/wet seasons. D. couperi in the Rookery Bay Reserve prefer upland habitats that feature various forms of refugia. These snakes also disproportionally use areas near roads and trailways. Detectability patterns for D. couperi in this reserve trend toward midday activity despite high ambient air temperatures, and had a higher detection probability during the breeding season. Compared to previous studies in the northern and central part of their distribution, D. couperi in the Rookery Bay Reserve demonstrate unique trends in home range sizes, seasonal activity, habitat and refugia usage, detectability patterns and general behavior. Unique habitat utilization and behavior of the species in its southernmost range highlights the need for different management strategies in southwest Florida. Understanding the ecological needs of this threatened species is imperative to their survival, particularly in south Florida as increasing human development continues. Florida Gulf Coast University
