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UBC Theses and Dissertations

Behavioral ecology of the bobcat in a region with deep winter snows. Newbury, Roberta Kay


The bobcat (Lynx rufus) is a native North American felid that is an economically valuable furbearer. This mesocarnivore is an important species in ecosystem structuring, exerting top-down control on rodent populations. Bobcats in northern latitudes face seasonal challenges such as deep snows, cold, and food scarcity. I used laboratory, modeling, and field methods to investigate bobcat ecology in a northern peripheral population where I evaluated, (1) winter diet, (2) modeled energetics and determined overwinter prey requirements, (3) determined home range size and habitat selection, and (4) determined seasonal movement distances and shape of movements in relation to habitat. Bobcats consumed 5 major prey groups: deer (Odocoileus spp.), snowshoe hares (Lepus americanus), red squirrels (Tamiasciurus hudsonicus), Cricetidae (rodents), and Tetraoninae (grouse). Squirrels accounted for 54% of biomass consumed, followed by Cricetidae (24.5%), hares (12.2%), deer (8.5%), and grouse (<1%). Bobcats in northwest Montana appeared to be dependent on squirrels and other rodents in the winter. I developed a strict, but realistic, winter energetics model for bobcats from field data on average movements, body mass, and observed diet of bobcats in northwest Montana. Bobcat daily energy expenditures were estimated at ~2.35×basal metabolic rate. This model predicted that over winter, a 10.5 kg bobcat would need ~5 kg of deer, 15 snowshoe hares, 338 red squirrels, 19 woodrats, and 547 small rodents. Male bobcat annual home ranges were 90.0 ± 12.0 km² and females were 42.2 km². Seasonal home ranges, within sex, did not differ significantly in size or relative habitat composition. Home range composition did differ from availability across the study site, with open habitats being chosen less and lodgepole pine (Pinus contorta) habitats been chosen more. Locations within the home range were found in most habitats according to availability. Male bobcats moved greater daily distances across seasons than did the female bobcat. Movement distances were significantly less in winter for both. Fractal dimension of movement pathways show male bobcats moved in a more linear fashion, while the female exhibited more convoluted movements across all seasons. Males and the female differed in habitats selected along movement paths, but varied little across seasons.

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