Literaturdatenbank
Literaturdatenbank |
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Wilson, T. P. (2002). Microhabitat parameters and spatial ecology of the spotted turtle (clemmys guttata): a comparison among populations. Unpublished PhD Dissertation, George Mason University.
Added by: Admin (14 Aug 2008 20:35:33 UTC) Last edited by: Sarina Wunderlich (25 Sep 2008 17:27:51 UTC) |
| Resource type: Thesis/Dissertation BibTeX citation key: Wilson2002a View all bibliographic details  |
Categories: General Keywords: Clemmys, Clemmys guttata, Emydidae, Habitat = habitat, Nordamerika = North America, Schildkröten = turtles + tortoises Creators: Wilson Publisher: George Mason University |
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| Abstract |
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A comprehensive understanding of how habitat and environment influence a species' spatial ecology is central toward implementing adaptive conservation and management strategies. This dissertation represents an examination of the factors affecting home range size, movement patterns, annual and seasonal activity, habitat use and rates of habitat change. Specifically, the following hypotheses were investigated: (1) the influence of home range methodology on estimates of home range size; (2) the influence of body size or age on home range size; (3) are movement patterns, activity cycles, and habitat use similar across populations; and (4) the effect of land use practices on habitat composition. To achieve these objectives, 34 adult spotted turtles (Clemmys guttata) from three sites in eastern North America were radio-equipped to determine differences in spatial ecology and habitat use. In addition, aerial photography and ground truth surveys were used to assess relative rates of habitat change. Home range size and movement patterns did not differ significantly between genders or across sites, although females moved, on average, farther and had larger home ranges when compared to males. Significant differences between home range models were detected. Specifically, the Bivariate Normal Ellipse estimator was significantly larger when compared to the other methods used (i.e., Minimum Convex Polygon, Harmonic Mean, Adaptive Kernel, and Core Area). However, no significant difference was detected between the MCP, HM, and AK methods, although AK was not significantly different from the CA estimator. Overall, the results for home range resembled those of other well studied populations. The findings on movements and habitat use paralleled those of the home range analysis. Turtles did not select habitats randomly, but rather, turtles preferred habitats that provided ample water and cover in juxtaposition. These habitats were believed to provide the necessary resources for normal activity. The core areas or primary centers of activity were centralized around nesting, foraging, and overwintering areas. Annual activity was comparable across sites and to those in the literature. Daily survival rates were high, indicating a more than adequate radiotelemetric protocol. Habitat composition was structurally different across sites but species composition was similar. Rates of habitat change were estimated using aerial photography and ground truth surveys. Of the three sites, both the LT1 and LT3 study sites showed an overall increase in suitable habitat. This increase was attributed to active habitat management and a change in local land use practices. However, the amount of habitat lost at the OCTA study site was substantial, and if the present trend continues the resident population could be extirpated by 2004. A landscape approach to conservation is recommended and should involve active habitat management, the creation of vegetative buffer zones, and the removal of exotic plants. Furthermore, an approach that involves local residents may change the prevailing attitudes toward habitat conservation. A holistic approach that incorporates a metapopulation dynamic will be required if these populations of Clemmys guttata are to be sustained in perpetuity.
Added by: Admin Last edited by: Sarina Wunderlich |