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Doctor of Philosophy (PhD)
Wildlife & Fisheries Conservation
Year Degree Awarded
Month Degree Awarded
Todd K. Fuller
John F. Organ
Terrestrial and Aquatic Ecology
Although black bears (Ursus americanus) are among the most studied mammals in the world, little is known about their ecology in Newfoundland, Canada. I investigated the spatial ecology of black bears on the island, focusing on unusual movements during the denning period and their role as caribou (Rangifer tarandus) calf predators.
I investigated the influence of climatic conditions (rainfall) and anthropogenic disturbance on the rate of den abandonment for black bears in Newfoundland, a population with an unusually high rate of abandonment given its northern latitude. I found no evidence that rainfall or anthropogenic disturbance played a role in den abandonment. My results may provide preliminary background rates of den abandonment for a northern and relatively remote ecosystem, with which to assess future change.
I examined black bear predation of caribou neonates using long-term mortality and location data from 21 bears and 308 caribou. I investigated the influence of landscape features on calf vulnerability, evaluated if bears actively hunted calves, and assessed the impact of changes in the abundance and vulnerability of calves on the foraging strategy of bears. I found that landscape heterogeneity influenced calf vulnerability, and that bears selected areas where they were most likely to kill or encounter calves. Initially, daily kill rates varied with calf abundance in a type-I functional response, but, as calf vulnerability declined, kill rates dissociated from abundance. Bears adjusted their foraging strategy based upon the efficiency with which they could catch calves, highlighting the influence of predation phenology on predator space use.
Most bear predation of calves occurs when caribou are aggregated on calving grounds. Some bears visit calving grounds (visitors), and thus have opportunities to prey on calves, whereas others do not (non-visitors). I evaluated differences in resource selection patterns between 4 visitor and 2 non-visitor populations (56 bears). Visitors showed stronger selection than non-visitors for local-scale landscape features associated with increased mortality risk for calves, but selection patterns were not entirely consistent among visitors and non-visitors. At the landscape-scale, most visitors displaying stronger selection than non-visitors for open landscape features associated with an increased probability of encountering caribou calves.
Rayl, Nathaniel D., "Spatial Ecology of Black Bears (Ursus americanus) in Newfoundland, Canada" (2017). Doctoral Dissertations. 899.