The Wolf Intelligencer


Barren-Ground Caribou (Rangifer tarandus groenlandicus) North America

Critical summer foraging tradeoffs in a subarctic ungulate. Ehlers L, Coulombe G, Herriges J, Bentzen T, Suitor M, Joly K, Hebblewhite M. Ecology and Evolution. 2021 Dec


Summer diets are crucial for large herbivores in the subarctic and are affected by weather, harassment from insects and a variety of environmental changes linked to climate. Yet, understanding foraging behavior and diet of large herbivores is challenging in the subarctic because of their remote ranges. We used GPS video-camera collars to observe behaviors and summer diets of the migratory Fortymile Caribou Herd (Rangifer tarandus granti) across Alaska, USA and the Yukon, Canada. First, we characterized caribou behavior. Second, we tested if videos could be used to quantify changes in the probability of eating events. Third, we estimated summer diets at the finest taxonomic resolution possible through videos. Finally, we compared summer diet estimates from video collars to microhistological analysis of fecal pellets. We classified 18,134 videos from 30 female caribou over two summers (2018 and 2019). Caribou behaviors included eating (mean = 43.5%), ruminating (25.6%), travelling (14.0%), stationary awake (11.3%) and napping (5.1%). Eating was restricted by insect harassment. We classified forage(s) consumed in 5,549 videos where diet composition (monthly) highlighted a strong tradeoff between lichens and shrubs; shrubs dominated diets in June and July when lichen use declined. We identified 63 species, 70 genus and 33 family groups of summer forages from videos. After adjusting for digestibility, monthly estimates of diet composition were strongly correlated at the scale of the forage functional type (i.e., forage groups composed of forbs, graminoids, mosses, shrubs and lichens; = 0.79, p < .01). Using video collars, we identified (1) a pronounced tradeoff in summer foraging between lichens and shrubs and (2) the costs of insect harassment on eating. Understanding caribou foraging ecology is needed to plan for their long-term conservation across the circumpolar north, and video collars can provide a powerful approach across remote regions.

Barren-Ground Caribou-a cyclic species: The development of a cycle-stratified harvest model and a cycle analysis of North American Barren-Ground Caribou subpopulations. Bongelli, E., 2019

Caribou (Rangifer tarandus) and Inuit nutrition security in Canada. Kenny TA, Fillion M, Simpkin S, Wesche SD, Chan HM. EcoHealth. 2018 Sep

Climate influences body condition and synchrony of Barren-Ground Caribou abundance in Northern Canada. Mallory CD, Campbell MW, Boyce MS. Polar Biology. 2018 May

Early fall and late winter diets of migratory caribou in northwest Alaska. Joly K, Cameron MD. Rangifer. 2018 Mar

Undermining subsistence: Barren-Ground Caribou in a “tragedy of open access”. Parlee BL, Sandlos J, Natcher DC. Science advances. 2018 Feb

Advancing the match-mismatch framework for large herbivores in the Arctic: Evaluating the evidence for a trophic mismatch in caribou. Gustine D, Barboza P, Adams L, Griffith B, Cameron R, Whitten K. PLoS One. 2017 Feb

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A mineral lick of the Barren-Ground Caribou. Calef GW, Lortie GM. Journal of Mammalogy. 1975 Feb

Distribution and densities of wolves within Barren-Ground Caribou range in northern mainland Canada. Parker GR. Journal of Mammalogy. 1973 May