Home Range and Movements of the Tortoise Gopherus polyphemus in Northern Florida

Abstract

-Twenty-two gopher tortoises (Gopherus polyphemus) were fitted with radio transmitters and tracked for up to two years. Considerable individual variation was observed in home range size, distances moved, duration of winter inactivity, and number of burrows used. Mean home ranges were 0.88 ha for adult males and 0.31 ha for adult females. Mean home ranges for subadults (0.05 ha) and juveniles (0.01 ha) were smaller, but three immature tortoises had ranges comparable to or larger than those of some adults. The longest recorded movement (0.74 km) was made by a dispersing subadult. Burrow defense, burrow usurpation, overnight co-occupation, and use of clearcuts, windrows, and flooded burrows were observed. rnal of Herpet logy, Vol. 26, No. 2, pp. 5865, 1992 right 1 92 Society for the Study of Amphibians and Reptiles e Range and Movements of the Tortoise Gopherus polyphemus in Although more widely distributed in Florida than in the other five southeastern states where it occurs, the gopher tortoise (Gopherus polyphemus) is declining because of rampant urbanization (Auffenberg and Franz, 1982; Diemer, 1987a). The species' legal status in the six states lthough more widely distributed in Florida r nges from endangered (Mississippi, South Carolina) to unlisted (Louisiana). The gopher tortoise receives federal protection as a threatened species in southeastern Louisiana, southern Mississippi, and southwestern Alabama. In Florida, the gopher tortoise is a Species of Spe158 This content downloaded from 207.46.13.11 on Wed, 10 Aug 2016 06:21:56 UTC All use subject to http://about.jstor.org/terms GOPHER TORTOISE HOME RANGE cial Concern. This reptile is currently the focus of mitigation and habitat preservation efforts on upland sites slated for development (Diemer, 1987b). Accordingly, requests for information regarding its home range size are increasing. Unpublished data regarding gopher tortoise home range and movements are presented in several theses (Wright, 1982; Bard, 1989; McLaughlin, 1990; Wilson, 1990). Although other pertinent findings exist in the literature (Douglass and Layne, 1978; Auffenberg and Iverson, 1979; Douglass, 1986), only one published study directly addresses the movement patterns of telemetered, resident gopher tortoises (McRae et al., 1981b). Other telemetry studies have focused primarily on gopher tortoise response to relocation (Fucigna and Nickerson, 1989; Godley, 1989; Layne, 1989; Stout et al., 1989). This study was conducted in conjunction with an investigation of gopher tortoise demography. Preliminary data from 1982-1984 revealed lower recapture rates on a north Florida site disturbed by pine planting than in more homogeneous sandhill habitat (Diemer, unpubl. data). McRae et al.'s (1981b) study of tortoise movements was conducted on a Georgia sandhill. I, therefore, chose to telemeter tortoises in pine plantations to better understand their population dynamics and to compare their movements with those in the Georgia study. The specific objectives of my study were to determine the following for both adult and immature tortoises: (1) home range size and distances moved; (2) seasonality of movements and burrow use; (3) social interactions; and (4) response to habitat modifications.