AUTHORS: Shauna S. Sayers, School of Forestry and Horticulture, Southern Illinois University; Brent S. Pease, School of Forestry and Horticulture, Southern Illinois University; Michael V. Cove, North Carolina Museum of Natural Sciences.
ABSTRACT: Non-native invasive species are a leading contributor to global biodiversity loss. The Burmese python (Python bivittatus), a large constrictor snake native to Southeast Asia, is one of Florida's most notable exotic predators. Although python’s prey vary in size and species, rodents are the most common group detected in their digestive tracts. The Key Largo woodrat (Neotoma floridana smalli) and Key Largo cotton mouse (Peromyscus gossypinus allapaticola) are two endangered rodent subspecies, endemic to Key Largo, Florida, that are susceptible to the threat of increasing python prevalence. We examined the impact of Burmese pythons on these two subspecies by conducting spatial capture-recapture surveys at 23 grids and deploying remote cameras at 629 supplemental woodrat nests across North Key Largo from January to August 2024. Trapping effort concluded with a total of 4,309 trapnights, capturing 37 woodrats (17 individuals) and 268 cotton mice (152 individuals). The effects of python presence on woodrat and cotton mouse populations were examined by comparing current rodent abundance estimates to those estimated during the python’s apparent establishment and increasing prevalence. Our results indicate the abundance of woodrats and cotton mice has declined coinciding with the increasing detections of pythons, with more drastic declines in the larger woodrats. Preliminary SECR estimates show a decrease in woodrat density from 0.48 individuals per hectare in 2017 to 0.08 individuals per hectare in 2024. Furthermore, our analysis demonstrated that areas with higher python activity exhibited altered habitat use patterns by woodrats such as decreased nest use and stick-nest building. These results suggest that as pythons increase their population size and distribution, the already geographically limited woodrats and cotton mice may continue to experience population declines and shifting habitat use.
