Gopher Tortoise (Gopherus polyphemus) Burrow Densities in Scrub and Flatwoods Habitats of Peninsular Florida

Gopher tortoises (Gopherus polyphemus) occur in a variety of habitats, but are primarily associated with sandhill communities. In peninsular Florida, however, mesic flatwoods make up the largest area of habitat, and scrub often replaces sandhill on inland ridges. Tortoise ecology is poorly understood in these habitats and few data are available to guide management. We surveyed tortoise burrows and assessed vegetation in scrub, flatwoods, and pine plantations on flatwoods soils at Avon Park Air Force Range in south-central Florida. Densities of noncollapsed burrows in scrub (1.93/ha) and flatwoods/plantations (1.42/ha) were generally lower than is typical for sandhill (3.25-9.95/ha), although total abundance was high (>20,000) because of the large habitat area. In scrub, low burrow densities may be due to low abundance of food plants. Nonetheless, the burrow density in scrub was significantly higher than in flatwoods/plantations, where food was abundant but soils were poorly drained and burrows were often flooded. The percentage of collapsed burrows was significantly higher in scrub (53%) than in flatwoods/plantations (35%), although a higher percentage of the remaining (noncollapsed) burrows were active in scrub (23%) than in flatwoods/plantations (16%). These patterns (and data from a subsequent radiotelemetry study) suggest that tortoises in scrub maintain strong fidelity to individual burrows, and frequently abandon others, whereas tortoises in flatwoods share burrows and move among them regularly, but rarely abandon them. This sharing and continual reuse of available burrows suggests a possible limitation on suitable conditions for burrow construction in flatwoods, probably related to the high water table. We suggest that scrub and flatwoods may constitute suboptimal habitats for gopher tortoises, due to low abundance of food in scrub and poorly drained soils in flatwoods. Nonetheless, large numbers of tortoises may occupy scrub and flatwoods, necessitating better understanding of their ecology in these habitats.