Document: JEF-3-81-3

Area requirements of Gopher Tortoises (Gopherus polyphemus): Re-evaluating guidelines for estimating reserve size.

OTT, J.A.* ¹, J.W.HOLLISTER ¹, C.GUYER ² and W.K.MICHENER ¹

Joseph W. Jones Ecological Research Center Newton GA 31770 USA ¹
Auburn University Auburn AL USA ²

Abstract:
Gopher tortoise (Gopherus polyphemus) populations have declined because of habitat loss and fragmentation. Guidelines based on estimates of individual space requirements for tortoises were previously developed in remnant habitat patches, and indicated that reserves be 10 - 20 ha in size and contain 80 burrows to support viable tortoise populations. However, home range data used to develop these guidelines underestimate general patterns and, thus, may influence reserve size estimates. Over a one-year period, 123 tortoises were tracked in Baker County, Georgia and the data used in a GIS to create artificial reserves. We compared each guideline to area and burrow use patterns of the actual population. Our data suggest that home range poorly estimated reserve size. Estimates based on burrow counts were more accurate in determining reserve area. Mean reserve size was 16.2 0.29 ha with a mean population size of 47.7 0.33 tortoises. No reserve was smaller than 10 ha and only 11% of reserves were larger than 20 ha. Only 1% of reserves contained populations smaller than 40 individuals, the minimum value for a viable population. Future studies should re-calculate minimum viable population size with more recent models to ensure that adequate habitat is protected for viable gopher tortoise populations.

Keywords: gopher tortoise, Gopherus polyphemus, reserve size

This abstract is being presented at: 3:30 PM in session:
CONSERVATION ECOLOGY