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Gopherus polyphemus Research Procedures in the Christopher B. Smith Preserve 2008
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© Photographs and text by the Science Division of the Conservancy of Southwest Florida, unless otherwise credited above.
Gopherus polyphemus Research Procedures in the Christopher B. Smith Preserve 2008
1) The entire parcel was systematically surveyed for gopher tortoise burrows. A preconstruction photograph of the property (shown at right) was used during the survey.
2) Each burrow was flagged and numbered. The width of each burrow was measured with a forester's caliper and the location recorded with a Global Positioning System (GPS).
3) The status of each burrow was determined to be active (tracks or scrape-marks indicating recent tortoise activity), inactive (no observable activity), or abandoned (overgrown or damaged). Activity was also determined by placing small sticks in the ground at the entrance to the burrow.
4) A telescopic video camera was used to check burrow occupancy and the presence of burrow commensals.
5) The distribution of burrows was mapped and analyzed using geographic information system (GIS) software.
6) Tortoises were captured by hand and using bucket traps. Bucket traps consisted of 5 gal. buckets with drainage holes in the bottom were buried at the entrance of active burrows. Efforts were made to limit disturbance to nests beneath the burrow apron and traps were not used if a nest was detected. Buckets were checked twice daily when trapping tortoises. Additionally, Sherman traps and screen funnel traps were set near the entrances of burrows to document the presence of commensals. Trapping/collecting was conducted intensively during the initial phase of the proposed study in order to capture all tortoises inhabiting the parcel, and then for one week each month thereafter when tortoises are active.
7) As shown below, each tortoise was measured (carapace length and width, plastron length, and gular projection length), weighed, sexed, and given an individual identification code. A number was painted on its carapace. Identification notches were cut into the marginal scutes of young tortoises and identification holes were drilled into the marginal scutes of older individuals. Age was estimated by counting plastral annuli and ventral and dorsal digital photographs were taken of each animal.
8) Food items were identified by observation of tortoise feeding and the collection of fecal samples. Tortoises were held 24-48 hours in shaded plastic bins at the Conservancy’s facilities for fecal sample collection.
Photograph of adult eating: Courtesy of Susan Leach Snyder, Conservancy of Southwest Florida volunteer.
9) Standard protocols were used to collect blood samples from a subsample of tortoises to test for Upper Respiratory Tract Disease.
10) As shown below, after data collection, tortoises were released at the site of capture.
11) Capture and diet data were analyzed with respect to body size, age, and sex classes. Data from recaptured tortoises were used to calculate growth rates and to construct von Bertalanffy growth models.
© Photographs and text by the Science Division of the Conservancy of Southwest Florida, unless otherwise credited above.
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