Literaturdatenbank
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Hedman, H., Pagan, D. M., & Powell, R. , Chelonoidis carbonaria (red-footed tortoise) size and thermal biology - abstract. Unpublished paper presented at Program and Abstracts of the Tenth Annual Symposium on the Conservation and Biology of Tortoises and Freshwater Turtles.
Added by: Admin (06 Jan 2014 18:22:51 UTC) |
| Resource type: Conference Paper BibTeX citation key: Hedman2012 View all bibliographic details  |
Categories: General Keywords: Chelonoidis carbonaria, Habitat - habitat, Mittelamerika - Central America, Schildkröten - turtles + tortoises, Testudinidae Creators: Hedman, Pagan, Powell Collection: Program and Abstracts of the Tenth Annual Symposium on the Conservation and Biology of Tortoises and Freshwater Turtles |
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| Abstract |
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Testudinidae Geochelone The understanding of tortoise natural history and demography is crucial for future management and conservation purposes. From 4–19 June 2010, we encountered 62 Red-footed Tortoises (Chelonoidis carbonaria) on Union Island, St. Vincent and the Grenadines. The origin of the Union Island population is unknown. Tortoises were abundant in a variety of habitats at elevations ranging from sea level to >250 m. Carapace lengths of tortoises large enough for accurate determinations of sex were 248–334 mm (x¯ = 301 ± 25.1 mm) for males (N = 11) and 152–330 mm (x¯ = 264 ± 56.9 mm) for females (N = 17). Carapace lengths of ten 6–8 week-old juveniles hatched in an outdoor enclosure were 45–63 mm (x¯ = 55 ± 5.1 mm). The smaller maximum sizes of Union Island tortoises are suggestive of insular dwarfism compared to mainland Central and South American populations. We encountered all but one active turtles during the morning (0538–0919 h, N = 6) and afternoon/evening (1500–2256 h, N = 22). To test the prediction that tortoises on Union Island did not actively thermoregulate, we used a Fluke model 52 Digital Thermometer with Type K thermocouple (Fluke Corp., Everett, Washington, USA) to record cloacal and adjacent ambient (air) temperatures in the field. We measured cloacal temperatures of 26.0–34.6°C (x¯ = 28.1 ± 1.3°C, N = 19) at air temperatures of 25.3–30.8°C (28.9 ± 1.8°C). We also placed nine individuals (carapace length 45–172 mm, x¯ = 88 ± 56 mm) in a thermal gradient (90 x 30 cm) with extreme temperatures of 24 and 40°C. Although most individuals spent more time near the cooler end of the gradient, cloacal temperatures after 2 h were 23.9–31.6°C (x¯ = 26.5 ± 2.7°C). The considerable variation in individual temperatures in both the field and the gradient was suggestive of little more than an avoidance of extremely high temperatures. The avoidance of higher temperatures suggests greater thermoregulation for island tortoises because of a greater access to sunlight compared to tortoises dwelling in the forested mainland. This study offers the first recorded notes of morphology and thermoregulation for Red-footed Tortoises on Union Island.
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