Nesting ecology, female home range and activity, and population size-class structure of the gopher tortoise, Gopherus polyphemus, on the Katharine Ordway Preserve, Putnam County, Florida

Abstract

From 1989 to 1991, I conducted field observations on life history characteristics of the gopher tortoise (Gopherus polyphemus) on the Katharine Ordway Preserve in north-central Florida. Fourteen adult females were radio-instrumented for up to 505 days to determine home range size, movement, and activity patterns. Home range estimates varied greatly among individual females ranging between 0.002 and 1.435 ha Burrow densities ranged between 2.42 and 10.56 ha. The overall population size-class structure was skewed toward adults (> 210 mm carapace length), suggesting a stable or declining population. Over three consecutive nesting seasons, 2008 burrow aprons were checked for eggs. Less than two percent of the aprons contained nests and only two of 18 gravid females deposited their eggs at burrow entrances. The mean clutch size in 1990, at the height of a long term regional drought. was significantly different from 1991, when seasonal rainfall was near average. Clutch size was positively correlated with female carapace length although carapace length explained only a small amount of the variance. However, a negative correlation between burrow width and clutch size at nests located in burrow aprons suggests that these nests may have been deposited by nonresident females.