Université Laval
Ph.D. candidate
Supervisor: Dominique Berteaux
Gilles Gauthier, Université Laval
Start: 2011-09-03
End: 2016-07-27

Project

Direct and indirect effects of predation on lemmings in the High Arctic
Wildlife populations are affected by large-amplitude, cyclic fluctuations of abundance and these have long fascinated ecologists because of the complex mechanisms involved in their regulation. Although both bottom-up (i.e. resources) and top-down (i.e. predation) forces have been shown to drive population cycles under some circumstances, there are still debates over which of these forces is primarily responsible for regulating lemming cycles in the High Arctic. Brown lemming (Lemmus trimucronatus) populations found on Bylot Island, Sirmilik National Park, Nunavut, are characterized by 3 to 4-year population cycles. Previous studies indicated that brown lemmings only consume a small fraction of the total plant biomass available at this site during winter, and thus food limitation is unlikely to drive these cycles. Furthermore, a related study demonstrated that, although quality of the snow cover may affect the amplitude of cycles, change in snow quality due to recent increases in temperature were not large enough to disrupt the cycles. However, results of these studies suggested that predation may be involved in generating lemming cycles on Bylot Island. Direct mortalities caused by high predation rate have often been identified as an initiating factor for population cycles. Predation may also be responsible for indirect effects which, through maternal effects, could potentially reduce recruitment of the prey. We will test the hypothesis that predation can drive brown lemming population cycles in the Canadian Arctic through a combination of both direct (i.e. lethal) and indirect (i.e. non-lethal) effects. We have excluded most predators over a large area (8 ha) with both a fence and a net, built in the summer of 2012, when lemming populations and their predators were in the low of the cycle. We are live-trapping lemmings in a grid located inside the exclosure and one outside it (control) three times each summer in 2012, 2013, and 2014 to estimate their abundance, survival and recruitment rate. The non-lethal effects of predation are measured by assaying the stress hormones (i.e. corticosterone) found in lemming faeces. We will first proceed with a validation to quantify the relationship between blood corticosterone and fecal corticosterone metabolites that are produced after a stressful event. Terrestrial predators (i.e. arctic fox, Vulpes lagopus, and short-tailed weasel, Mustela erminea) will be monitored with a combination of signs of predation in winter nests, snow tracks, live-traps (for weasels) and direct observations. According to our hypotheses, we predict that the abundance, survival and recruitment rate will be higher inside the enclosure than outside it during both peaks and lows. We predict that the stress of lemmings will be lower inside the enclosure compared to outside. Finally, we predict that stress of lemmings will be higher in years of high abundance and high predation rates compared with years of low abundance and low predation rates.

Keywords

lemming cycles, predation, stress, exprimental manipulation, winter nests, survival, population dynamics

Publications

1- Cyclic dynamics of a boreal southern red-backed vole population in northwestern Quebec
Fauteux, Dominique, Marianne Cheveau, Louis Imbeau, Pierre Drapeau
2015 Journal of Mammalogy

2- Does lemming winter grazing impact vegetation in the Canadian Arctic?
Bilodeau, Frédéric, Gilles Gauthier, Dominique Fauteux, Dominique Berteaux
2014 Polar Biology

3- Small mammal responses to coarse woody debris distribution at different spatial scales in managed and unmanaged boreal forests
Fauteux, Dominique, Louis Imbeau, Pierre Drapeau, Marc J. Mazerolle
2012 Forest Ecology and Management

4- Site occupancy and spatial co-occurrence of boreal small mammals are favoured by late-decay woody debris
Fauteux, Dominique, Marc J. Mazerolle, Louis Imbeau, Pierre Drapeau
2013 Canadian Journal of Forest Research

5- Top-down limitation of lemmings revealed by experimental reduction of predators
Fauteux, Dominique, Gilles Gauthier, Dominique Berteaux
2016 Ecology

6- Seasonal Demography of a Cyclic Lemming Population in the Canadian Arctic
Fauteux, Dominique, Gilles Gauthier, Dominique Berteaux
2015 Journal of Animal Ecology