Anti-predator behaviour of maternal caribou (Rangifer tarandus) in west-central Newfoundland

Soulliere, Colleen Evelyn (2008) Anti-predator behaviour of maternal caribou (Rangifer tarandus) in west-central Newfoundland. Masters thesis, Memorial University of Newfoundland.

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Abstract

Caribou (Rangifer tarandus) calf survival largely depends on the physiological condition and behaviour of the mother, and her resulting ability to provide her calf with nourishment and protect her calf from harm. Calf mortality in Newfoundland's insular herds has increased dramatically in recent years, concurrent with a change in predator guild. Passive (vigilance) and active (response to disturbance) aspects of maternal anti-predator behaviour in the Gaff Topsail herd, west-central Newfoundland, were studied to gain an understanding of their implications for calf survival. -- The group-size effect on vigilance was only observed for adult female caribou engaged in foraging behaviour, indicating a foraging-vigilance trade-off exists (foraging increased and vigilance decreased when competition for local resources increased). Time-activity budgets did not differ between females with calves and those without; however, maternal caribou fed more intensely and were less frequently vigilant. When disturbed, maternal caribou were usually the first individuals to run and, particularly during the peri-calving season, separated from and ran further than other group members. -- Consistent with other evidence, this study supports the hypothesis that Newfoundland's insular caribou are currently facing nutrient stress. The reduction of vigilance in favour of foraging may additively contribute to predation vulnerability of calves. Aspects of maternal caribou response to disturbance indicate low levels of perceived safety but may increase calf vulnerability to stalking or coursing predators.

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