University of Alberta

Rob Serrouya

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1992 - 1994, B.Sc. McGill University, Wildlife Resources
1995 - 1999, M.Sc. University of British Columbia, Conservation Biology
2008 - 2013, Ph.D. University of Alberta, Department of Biological Sciences

PhD Thesis Title

An adaptive approach to endangered species recovery based on a management experiment: reducing moose to reduce apparent competition with woodland caribou.

Project Summary

Species that are rare yet widely distributed are among the most challenging to conserve. The mountain ecotype of woodland caribou (Rangifer tarandus) is declining because of apparent competition with non-caribou ungulates (NCU) such as moose (Alces alces). I experimentally assessed whether reducing NCU could facilitate caribou recovery by taking advantage of a government policy to reduce moose abundance with increased hunting. First, I used microsatellite markers to evaluate the evolutionary significance of the mountain ecotype, and determined whether previously identified subpopulations were demographically distinct. I found that subpopulation structure was mainly caused by genetic drift in small populations. The demographic isolation of many subpopulations suggests that they are appropriate as management units for recovery planning. I then developed an ecological target for recovering caribou by estimating the abundance of moose that would have occurred in the absence of forest harvesting. I incorporated this target into predator-prey equations to make predictions about the risks and benefits to caribou. Predictions suggest that reducing NCU without reducing predators could negatively impact caribou. The predicted impact was greater if there was a time lag of the predators’ numerical response, but gradually reducing NCU could mitigate this impact. Once the moose reduction was initiated in the field, the decline in moose numbers was greater than could be explained by the hunting treatment alone. I contrasted several hypotheses to explain the rate of decline, including density dependent, depensatory, or compensatory predation by wolves (Canis lupus). I found that depensatory predation best explained the moose decline, but hunting was the catalyst. Reducing moose appeared to reduce wolf numbers, with dispersal the likely mechanism. Remaining wolves spent more time in caribou habitat, but based on scat and kill-site investigations, there was no evidence that wolves shifted their diet to caribou. In the treatment and reference areas, the caribou response was mixed, with the larger subpopulations stabilizing but smaller ones continued to decline. By combining theoretical predictions with empirical manipulations I conclude that reducing NCU and predators concurrently is a prudent approach to recover caribou. Few broad-scale manipulations exist to recover endangered species, but are needed to evaluate recovery options.

Recent Publications

Wittmer, H. U., R. Serrouya, L. M. Elbroch, and A. J. Marshall. 2013. Conservation strategies for species affected by apparent competition. Conservation Biology 27:254–260.

Serrouya, R., D. Paetkau, B.N. McLellan, S. Boutin, Jenkins D. and M. Campbell. 2012. Population size and major valleys explain microsatellite variation better than taxonomic units for caribou in western Canada. Molecular Ecology 21: 2588–2601.

McLellan, M.L., R. Serrouya, B.N. McLellan, K. Furk, D. Heard, H.U. Wittmer. 2012. Implications of body condition on the unsustainable predation rates of endangered mountain caribou. Oecologia 169:853–860.

Boutin,S. M.S. Boyce, M. Hebblewhite, D. Hervieux, K.H. Knopff, M.C. Latham, A.D. Latham, J. Nagy, D.R. Seip, R. Serrouya. 2012. Why are caribou declining in the Oil Sands? Frontiers in Ecology and the Environment.

Serrouya, R., B.N. McLellan, G. Pavan, and C.D. Apps. 2011. Grizzly bear selection of avalanche chutes: testing the effectiveness of forest buffer retention. Journal of Wildlife Management 75:1597–1608.

Serrouya, R., B.N. McLellan, S. Boutin, D.R., Seip, and S.E. Nielsen. 2011. Developing a population target for an overabundant ungulate for ecosystem restoration. Journal of Applied Ecology 48: 935–942.

van Oort, H., B.N. McLellan, and R. Serrouya. 2011. Metapopulation or predictable pattern of extinction? Animal Conservation 14:231-232.

(Editor’s Choice) van Oort, H., B.N. McLellan, and R. Serrouya. 2011. Fragmentation, dispersal and metapopulation function in remnant populations of endangered mountain caribou. Animal Conservation. 14: 215–224.

Serrouya, R., and H.U. Wittmer. 2010. Imminent extinctions of woodland caribou from National Parks. Conservation Biology 24:363-364.

McLellan, B.N., R. Serrouya, H.U. Wittmer, and S. Boutin. 2010. Predator-mediated Allee effects in multiple-prey systems. Ecology 91: 286-292.

Wittmer, H.U., B.N. McLellan, R. Serrouya, and C.D. Apps.  2007. Changes in landscape composition influence the decline of a threatened woodland caribou population. Journal of Animal Ecology, 76:568–579.

Poole, K.G., R. Serrouya, and K. Stuart-Smith.  2007. Moose calving strategies in interior montane ecosystems. Journal of Mammalogy. 88:139–150.


Slightly more than a hobby, I like to play outdoors with my family, Sylvia, Carlos, and DOAT (AKA Ruby, the Destroyer Of All Things), usually on skis in the backcountry.

Contact Information

Rob Serrouya
Phone: (250) 837-7767

Last Modified:2013-05-28