UBC Theses and Dissertations
Effects of anthropogenic disturbance and wolf population reduction on caribou predators and competitors in west-central Alberta Seip, Caroline Rose
Woodland caribou are a threatened species in Alberta and across Canada, due to anthropogenic disturbances, such as forest harvest and linear features, which facilitate increased predation on caribou. To aid caribou recovery, the Government of Alberta is working to conserve areas of existing caribou habitat, recover habitat on linear features, and annually reduce wolf abundance. These management actions are beneficial for caribou, but potential effects on other wildlife have rarely been tested. To better understand any effects, we conducted multispecies surveys using remote cameras (n=60) within and surrounding the Little Smoky caribou range in west-central Alberta. We hypothesized that changes in wolf occurrence rate would be the predominant factor influencing other wildlife, because they are the top predator on the landscape and have been shown to exert top-down control in other ecosystems. We predicted decreased wolf occurrence rate in areas of high wolf removal efforts would result in higher occurrences of coyotes and lynx, through decreased competition, and higher occurrences of moose, elk, and deer, through decreased predation. Our alternative hypothesis was that habitat disturbances would be the dominant factor determining species occurrences through bottom-up ecosystem control. We used GLMMs to test the effects of anthropogenic disturbance and wolf population reduction on several medium and large-bodied mammal species. As expected, wolf occurrence was negatively affected by wolf removals. Wolf population reduction reduced wolf occurrences annually, but wolves recolonized areas of high removal effort each year. Unexpectedly, mesopredator occurrences were positively associated with, and ungulate occurrences unaffected by, rates of wolf occurrence. These species were instead more strongly associated with anthropogenic habitat disturbances (forest harvest, linear features), and mesopredators occurrences were also associated with prey availability. Our results suggest that despite the direct effect of wolf removals on wolves, wolf population management did not have cascading effects on other wildlife in this system. Rather, bottom-up factors, such as habitat features and prey availability were the most important drivers affecting the medium- and large-bodied mammal community in west-central Alberta.
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