Literaturdatenbank
Literaturdatenbank |
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Leuteritz, T. E. J. (2002). Distribution, status, and reproductive biology of the radiated tortoise, geochelone radiata (shaw, 1802) in southwest madagascar. Unpublished PhD Dissertation, George Mason University.
Added by: Admin (14 Aug 2008 20:35:29 UTC) Last edited by: Sarina Wunderlich (25 Sep 2008 17:27:17 UTC) |
| Resource type: Thesis/Dissertation BibTeX citation key: Leuteritz2002a View all bibliographic details  |
Categories: General Keywords: Astrochelys, Astrochelys radiata, Fortpflanzung = reproduction, Geochelone, Habitat = habitat, Madagaskar = Madagascar, Schildkröten = turtles + tortoises, Testudinidae Creators: Leuteritz Publisher: George Mason University |
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| Abstract |
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Testudinidae The objectives of this study were to examine the status and distribution of Geochelone radiata in southern Madagascar; to examine the extent of variation in tortoises occurring across the range; to examine, via a field study, the reproductive biology; to gather ancillary data on growth, diet, movements, external parasites, and thermal ecology; and to use this information to help improve conservation activities. The project was designed to examine these parameters in the field over a three-year period; specifically during the tortoises' active season (rainy season—November to April). Mating behavior was observed in the wild on numerous (n = 54) occasions at Cap Sainte Marie and in other locations from November to May; 45% of the observations occurred in December. Based on 24 observed nests, oviposition took place from February to May, with 38% of occurrences in April. Individual females at Cap Sainte Marie were multiple clutching, producing from 1–3 clutches per season (mean = 1.7 ± 1.1, n = 12). Hatchling success was high and consistent between years; 65.6% of eggs (9 nests, 32 eggs) hatched in 1999, and 66.7% of eggs (3 nests, 9 eggs) hatched in 2000. Tortoises range from south of Tulear to CSM. The estimated mean population size of radiated tortoises in the core of the range is between 12–54 million. Based on mtDNA extracted from blood samples gathered across the range, tortoise populations do not appear to exhibit phylogeographic structure. Female tortoises ranged in CL from 28–35.6 cm (mean = 31.9 cm) and weighed from 4.3–8.4 kg (mean = 6.3 kg). Male tortoises ranged in CL from 25.8–37.7 cm (mean = 31.2 cm) and weighed from 2.5–8.8 kg (mean = 5.2 kg). There was no significant difference in body size between males and females (t = 1.19, df = 48, P > 0.05). The compressed SDI, using CL as a measure of body size is 0.03. Males generally first exhibit distinct secondary sexual characteristics at a CL of 26 cm and females at CL of 28 cm. One of the most encouraging things about radiated tortoise conservation is that their numbers are quite high. (Abstract shortened by UMI.)
Added by: Admin Last edited by: Sarina Wunderlich |