Body temperature variation affects most physiological processes in terrestrial ectotherms and, therefore, can have a large effect on fitness. I studied eastern milksnakes at the northern extreme of their range, in a thermally challenging environment. Because of the particular importance of thermoregulation in thermal extremes, I hypothesized that thermal quality would influence thermoregulation, behaviour and habitat selection.
In chapter one, I demonstrated that when thermal quality decreased, milksnakes increased investment in thermoregulation, a result contrary to the central prediction of the cost-benefit model of thermoregulation. Because ecotherms obtain heat from their environment, I predicted that when thermal quality was low, milksnakes would bask more and select higher thermal habitat. Milksnakes did not alter their habitat use in response to thermal quality. They did, however, alter their behaviour and were seen basking more and concealed less when thermal quality was low.
In chapter two, my main goal was to determine if thermal quality affected habitat selection at multiple scales. Supporting my prediction, thermal quality influenced habitat selection at both the home range scale and the location scale. At both scales, milksnakes selected high thermal quality habitats (rocky outcrops, fields, and edges) and avoided low thermal quality habitat (forest). At the microhabitat scale, milksnakes selected locations with open canopy and many rocks. As a secondary objective, I tested the ability of 4 m resolution IKONOS imagery to accurately quantify habitat selection at the scale of the locations used by each snake. Although not as accurate as traditional field methods, remote sensing showed promise in measuring habitat selection at that scale.
| Identifer | oai:union.ndltd.org:uottawa.ca/oai:ruor.uottawa.ca:10393/27025 |
| Date | January 2005 |
| Creators | Row, Jeffrey R |
| Publisher | University of Ottawa (Canada) |
| Source Sets | Université d’Ottawa |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 92 p. |
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