Biology (B.S.B.)

Document Type and Release Option

Thesis (restricted to Georgia Southern)

Faculty Mentor

Dr. David Rostal


The effects of fire on Gopherus polyphemus populations in a sandhill habitat, specifically their reproductive success, has not been extensively studied in Georgia. Here we present data on a long term comparison of the reproduction and habitat use under different management: long term active fire management vs limited management approach. Reproductive output, population structure, and habitat quality were compared over a 20 year period (1994 to 2014). The project took place at two sites: Fort Stewart Army Reserve (FSAR) which is managed aggressively for tortoises and George L Smith State Park (GLS) which only recently received some management for its population. Female tortoises at FSAR are significantly larger than females at GLS (GLS: 29.08±0.327cm, n=69, FSAR: 30.49±0.107cm, n=301, p=.0002). When the data was pooled, there was a significant difference in clutch size (GLS: 4.83± 0.177 eggs, n=44, FSAR: 6.565± 0.113 eggs, n=194). The linear regression of clutch size and carapace length show weak positive correlations for GLS and FSAR (r²=0.0129, 0.1401 respectively). Analysis of Covariance showed significant heterogeneity of the slopes suggesting that the larger females at FSAR are producing larger clutch sizes which is not seen at GLS (p=0.0368). Habitat results were similar to the 1994-1996 study. There was a significant difference in canopy and ground cover between the burrows and random points at GLS but not at FSAR. Tortoises at both sites are selecting habitat with low canopy and available ground forage however tortoises at FSAR are able to find more favorable available habitat throughout their range.

Available for download on Saturday, April 11, 2020