Summer Range Relationships of the Porcupine Caribou Herd, 1985 PDF Download

Author: Donald Edmund Russell
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ISBN:
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Languages : en
Pages : 18

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Book Description
"This study focuses on the summer range relations of the Porcupine caribou herd with particular attention to the behavioral responses of barren-ground caribou (Rangifer tarandus granti) as groups and individuals to blood-seeking and parasitic dipterans. Between mid-June and mid-August, caribou in the northern Yukon are periodically harassed by dipterans. The period of dipteran activity coincides with the critical time when caribou are restoring fat reserves depleted during winter, growing new hair and antlers, and lactating cows are producing milk for calves. Caribou experience physical irritation and blood loss to mosquitoes which emerge in late June and are active until early August. When mosquitoes are bothersome, caribou show signs of irritation by shaking their head, back, rump, or stomping their feet (Thompson, 1977). Adult warble flies (Hypoderma tarandu and nasal bot flies (Cephenamya trompe), collectively know as oestrids, do not inflict pain but their presence cause caribou to exhibit a number of "annoyance responses" (Espmark, 1967). The larvae of oestrids are obligate parasites of R. tarandus and have direct and indirect effects on their hosts. a. Direct costs: mosquitoes - loss of blood; Oestrids - increased load of endoparasites feeding on lymph, possible allergic response, suppression of immune response (Dietrich, 1981). b. Indirect costs: The indirect effect of avoiding dipterans may include reduced feeding, resting or rumination time, decrease efficiency of grazing ie. feeding less selectively or feeding in less most favorable habitat. The behavioral responses to dipterans, as well as selection of habitat with few dipterans, may have evolved in response to the direct and indirect energy cost associated with encountering blood-seeking and parasitic dipterans"--Leaf 1.