High Arctic lemmings remain reproductively active under predator-induced elevated stress
Non-consumptive effects of predation have rarely been assessed in wildlife populations even though their impact could be as important as lethal effects. Reproduction of individuals is one of the most important demographic parameters that could be affected by predator-induced stress, which in turn can have important consequences on population dynamics. We studied non-consumptive effects of predation on the reproductive activity (i.e., mating and fertilization) of a cyclic population of brown lemmings exposed to intense summer predation in the Canadian High Arctic. Lemmings were live-trapped, their reproductive activity (i.e., testes visible in males, pregnancy/lactation in females) assessed, and predators were monitored during the summers of 2014 and 2015 within a 9 ha predator-reduction exclosure delimited by a fence and covered by a net, and on an 11 ha control area. Stress levels were quantified non-invasively with fecal corticosterone metabolites (FCM). We found that FCM levels of lemmings captured outside the predator exclosure (n = 50) were 1.6 times higher than inside (n = 51). The proportion of pregnant/lactating adult females did not differ between the two areas, nor did the proportion of adult scrotal males. We found that lemmings showed physiological stress reactions due to high predation risk, but had no sign of reduced mating activity or fertility. Thus, our results do not support the hypothesis of reproductive suppression by predator-induced stress.
KeywordsCyclic populations Top-down limitation Glucocorticoids Population regulation Reproduction suppression
The research relied on the logistic assistance of the Polar Continental Shelf Program (Natural Resources Canada) and of Sirmilik National Park. The research was funded by the Natural Sciences and Engineering Research Council of Canada (Discovery Grants and Frontiers to Discovery programs), the Northern Student Training Program of Indian and Northern Affairs Canada, the Canadian Network of Centres of Excellence ArcticNet, Environord, the W. Garfield Weston Foundation, and the Fonds de recherche du Québec—Nature et technologies. We thank Christine Lambert, Gabriel Montpetit, and David Gaspard for their help with the field work. We also thank all the Bylot Island field team for their assistance in this project. We thank Dennis Murray, Marc J. Mazerolle, Conrad Cloutier, Doug Morris, and Mark Hewitt for their constructive comments on a previous version of this manuscript.
All data used in this manuscript are available at the NordicanaD website: http://www.cen.ulaval.ca/nordicanad/en_index.aspx. http://dx.doi.org/10.5885/45400AW-9891BD76704C4CE2.
Author contribution statement
DF performed data collection in the field and in the laboratory, completed the statistical analyses, and wrote a complete draft of the manuscript; GG and DB co-supervised the project, performed data collection in the field, and significantly contributed to revisions of the text; RP and RB performed laboratory analyses and substantially contributed to revisions of the text.
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