Over 50% of the world’s human population resides in urban centres, and this is expected to increase as the global human population grows and people migrate from non-urban to urban centres. Concentrated in these urban areas are anthropogenic disturbances that impose additional challenges on wildlife compared to their non-urban counterparts. These challenges can be stress provoking. Through the release of corticosterone (CORT) reptiles can adapt to these stressors, physiologically and behaviourally, both in the short- and long-term. To investigate the relationships between stress activation and defensive tactics in wild urban Northwestern Gartersnakes (Thamnophis ordinoides) I conducted visual encounter surveys, along edge-focused transects, following a semi-constrained random sampling method. I sampled snakes at five sites, each with a different level of anthropogenic disturbance, in the Greater Victoria Area, BC. I sampled blood, observed anti-predator behaviour, and collected data on characteristics of snakes. The most disturbed site (with the most people, pets, and natural predators) also had the most snakes: those snakes also had highest H:L values (a proxy of CORT) in their blood compared to the other populations. Nevertheless, none of the snakes had H:L values that indicated chronic stress. Stress physiology was not correlated with anti-predator behaviour. More important to anti-predator behaviour was the size, sex/reproductive condition, and cloacal temperature of snakes. Although anthropogenic development can reduce habitat quality for some reptiles, Northwestern Gartersnakes coexist with recreationists at many sites in the District of Saanich. A multi-disciplinary approach is of paramount importance to understand the full effect of anthropogenic influences on wildlife. / Graduate / 0433 / 0329

Density dependence is a common phenomenon in nature, and the intensity of density dependence is driven by competition over depletable resources. Habitat selection patterns are often density-dependent, and are driven by decreasing population mean fitness in a habitat as population density increases in that habitat. Yet not all resources are depletable, and non-depletable resources may sometimes be most important in dictating patterns of habitat selection. Ectotherms, for example, are defined by their dependence on environmental temperature to regulate body temperature, and temperature is often the most important resource for ectotherms. Is density dependence an important mechanism in ectotherms, especially when temperature is a limiting factor? In this thesis, I examine density dependence of fitness and habitat selection by ectotherms using red flour beetles and common gartersnakes. In chapter one and three, I test whether density-dependent habitat selection occurs when habitats differ in both temperature and food availability with red flour beetles and common gartersnakes, respectively. In chapter two, I modify the isodar model of habitat selection to account for the effect of temperature on ectotherms, derive predictions from the modified model, and test these predictions with controlled experiments with red flour beetles selecting between habitats that differ in food quantity and temperature. Finally, in chapter four, I examine the effect of density on metrics of fitness and habitat selection with common gartersnakes. Red flour beetles exhibited strong density dependence in both habitat selection and fitness at their optimal temperature, but density dependence weakened at lower temperatures. Common gartersnakes exhibited mostly density-independent habitat selection with a strong preference for warm field habitat over cool forest habitat, but exhibited some density dependence in habitat selection within field habitat. Overall, my thesis demonstrates that ectotherms have variable density-dependent responses, and that these responses are strongly modulated by temperature.

abstract: Species conservation requires an understanding of the habitats on which that species depends as well as how it moves within and among those habitats. Knowledge of these spatial and temporal patterns is vital for effective management and research study design. Bubbling Ponds Hatchery in Cornville, Arizona, supports a robust population of the northern Mexican gartersnake (Thamnophis eques megalops), which was listed as threatened under the Endangered Species Act in 2014. Natural resource managers are interested in understanding the ecology of gartersnakes at this site to guide hatchery operations and to serve as a model for habitat creation and restoration. My objectives were to identify habitat selection and activity patterns of northern Mexican gartersnakes at the hatchery and how frequency of monitoring affects study results. I deployed transmitters on 42 individual gartersnakes and documented macro- and microhabitat selection, daily and seasonal activity patterns, and movement distances. Habitat selection and movements were similar between males and females and varied seasonally. During the active season (March–October), snakes primarily selected wetland edge habitat with abundant cover and were more active and moved longer distances than during other parts of the year. Gestating females selected similar locations but with less dense cover. During the inactive season (November–February), snakes were less mobile and selected upland habitats, including rocky slopes with abundant vegetation. Snakes displayed diurnal patterns of activity. Estimates of daily distance traveled decreased with less-frequent monitoring; a sampling interval of once every 24 hours yielded only 53–62% of known daily distances moved during the active season. These results can help inform management activities and research design. Conservation of this species should incorporate a landscape-level approach that includes abundant wetland edge habitat with connected upland areas. Resource managers and researchers should carefully assess timing and frequency of activities in order to meet project objectives. / Dissertation/Thesis / Masters Thesis Applied Biological Sciences 2017