Date of Award

9-1997

Type

Thesis

Major

Earth and Space Science - Environmental Science Track

Department

Earth & Space Science

First Advisor

David R. Schwimmer

Abstract

The movements and burrow use of twenty (ten relocated and ten indigenous to the relocation site) adult gopher tortoises {Gopherus polyphemus) were followed during the late spring, summer and early autumn in Talbot County, Georgia. The objectives of this study were to determine whether relocated gopher tortoises developed fidelity to a relocation site, and whether indigenous tortoises reacted adversely to relocated tortoises released in their proximity. Ten tortoises in the right-of-way of a highway construction project were captured, fitted with transmitters, and relocated to a 336 hectare tract of land, 3.2 km east of Geneva, Talbot, County, Georgia. Concurrently, ten tortoises indigenous to the relocation site were captured, fitted with transmitters, and returned to their burrows. Captured gopher tortoises were released into three areas separated by blackwater branch swamps along the northern edge of the relocation site: one area contained five indigenous tortoises; a second area contained five relocated tortoises; and a third area contained five indigenous and five relocated tortoises. Tortoises were tracked using a radio receiver from 22 May to 4 November 1 996. Their movements, azimuth, and burrow use were recorded initially every day for seven days following their release then every three days thereafter (weather permitting). Social interactions observed were also recorded. Two relocated tortoises left the relocation site and the transmitter on an indigenous tortoise failed within the first week after being released. A third relocated tortoise returned to the vicinity of its capture burrow immediately north of the relocation site, in late October. The remaining relocated and all indigenous tortoises stayed near their release burrows or traveled to new areas on the relocation site where they remained. Treatment (tortoises released in isolation, released with indigenous, or released with relocated tortoises), gender, and source (relocated or indigenous) had a significant effect on the behavior of the tortoises. Interactions among these variables were also significant. Males occupied more burrows and had a greater number of interburrow movements than females. Also, relocated tortoises released with indigenous tortoises or indigenous tortoises released with relocated tortoises occupied a greater number of burrows and had a greater number of interburrow movements than indigenous or relocated tortoises alone. The average distance traveled from the release burrow to each burrow occupied by a particular tortoise was found to be significant or highly significant for all examined factors; namely, treatment, gender, and source. Interactons between treatment, and/or gender, and/or source were also significant or highly significant. Tortoises released in areas with both indigenous and relocated tortoises moved a greater average distance than tortoises released in isolated areas. Males moved a greater average distance than females. Relocated tortoises (both sexes combined) moved a greater average distance than indigenous tortoises. Relocated female tortoises occupied the fewest burrows, moved the least number of times, and had the lowest average distance traveled compared to all tortoises studied. Because of the contrast in movement patterns among indigenous and relocated tortoises, only gender was found to be significant when the total distance traveled was compared. Due to wide variation among individuals in the distance moved from their release burrow to the last burrow occupied there was no significant difference in terms of gender, treatment, source, or their interactions. The 1 7 tortoises that were monitored for the duration of this study occupied 1 10 burrows and moved 193 times. Overall, males moved a total of 135 times compared to females who moved a total of 58 times. Seasonal differences in the number of movements were found to be significant. The number of movements recorded during July and August were approximately twice the number recorded during June, September, and October. Despite these differences the release of relocated tortoises among indigenous tortoises did not appear to have a pronounced negative impact on the latter group of tortoises. The movements patterns of relocated male tortoises towards the end of the study suggests they had become acclimated to the relocation site. The restricted movements of the relocated females may be due to repressive behavior by indigenous tortoises that were in close proximity to them.

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