Guyer Lab

Department of Biological Sciences, Auburn University

             Currently, we are examining the social dynamics related to the mating system of gopher tortoises. We hope to uncover the pattern of how these animals relate to each other in terms of physical distance, social structure, and how this may influence mating possibilities. By learning about these factors, we hope to discover how gopher tortoise communities are structured, which may be applicable to other species of tortoises that live communally.

Research Objectives:

             This is a long-term project. The roots of the project date back to 1988 when burrow surveys were started on the Conecuh National Forest (CNF) and the Wade Tract. At various times, the project has been expanded to include multiple sites in the CNF, Camp Shelby in Mississippi , a site in Alabama near Mobile, the Jones Ecological Research Center, and Fort Benning, in Georgia.

            

 

 

 

 

 

             The research focus has been multidimensional with the overarching goal of finding out what constitutes a population of tortoises, and how much area a population may require to maintain viability.  Many reports, theses, and peer-reviewed publications have been generated on movement patterns, growth patterns, population dynamics, social interactions, reproductive ecology, foraging ecology, and the influence of tortoises on microhabitat and vegetation structure as well as the effects of forestry/military activities on individual tortoises.

             Currently, we are exploring burrow co-occupancy (sharing of a burrow for 1 or more days), and behavioral interactions. We are finding that male-male co-occupancy occurs more frequently than expected given that gopher tortoises are thought to live in a society structured around dominant territorial males. Simplistically, in a male dominant society, a  male holds a territory or home range area, fights other males to keep them out, and thus garners breeding privileges to the females that are within their home ranges.  Observations of multiple male-male co-occupancy, including some pairs that reoccur multiple times throughout a year, seem inconsistent with the idea that males compete and combat each other regularly.

             We are also finding that female-female co-occupancy is rare. So far, the data show that within a site, one pair of females may occupy the same burrow once or twice, but rarely more often than that. Additionally, the females display aggression by mounting other females. And, female-male co-occupancy occurs about as frequently as do male-female co-occupancy. Meaning that a male joins a female in her burrow as often as a female joins a male in his burrow. Thus our data suggest that these societies may be female-dominated.

             We are exploring physical distance within sites between burrows occupied by interacting females and males, relatedness of individuals, nearest-neighbor aggression, and a social hierarchy based on body size as functions of the behavioral interactions that we see.

             In addition, we are collaborating with Dr. Mendonça on the subject of physiological stressors to gopher tortoises.