@article{5087fa64c5aa4040bf7473030d204af9,
title = "The impact of variable predation risk on stress in snowshoe hares over the cycle in North America{\textquoteright}s boreal forest: adjusting to change",
abstract = "The boreal forest is one of the world{\textquoteright}s ecosystems most affected by global climate warming. The snowshoe hare, its predators, and their population dynamics dominate the mammalian component of the North American boreal forest. Our past research has shown the 9–11-year hare cycle to be predator driven, both directly as virtually all hares that die are killed by their predators, and indirectly through sublethal risk effects on hare stress physiology, behavior, and reproduction. We replicated this research over the entire cycle by measuring changes in predation risk expected to drive changes in chronic stress. We examined changes in hare condition and stress axis function using a hormonal challenge protocol in the late winter of 7 years—spanning all phases of the cycle from the increase through to the low (2014–2020). We simultaneously monitored changes in hare abundance as well as those of their primary predators, lynx and coyotes. Despite observing the expected changes in hare–predator numbers over the cycle, we did not see the predicted changes in chronic stress metrics in the peak and decline phases. Thus, the comprehensive physiological signature indicative of chronic predator-induced stress seen from our previous work was not present in this current cycle. We postulate that hares may now be increasingly showing behavior-mediated rather than stress-mediated responses to their predators. We present evidence that increases in primary productivity have affected boreal community structure and function. We speculate that climate change has caused this major shift in the indirect effects of predation on hares.",
keywords = "Chronic stress, Climate change, HPA axis, Non-consumptive predator effects, Population cycles",
author = "Lavergne, {Sophia G.} and Krebs, {Charles J.} and Kenney, {Alice J.} and Stan Boutin and Dennis Murray and Rupert Palme and Rudy Boonstra",
note = "Funding Information: We thank the numerous assistants for help with the winter field work and hare monitoring and with laboratory sample preparation and analyses. We thank and recognize the late Peter Upton for his long-term contribution to the winter predator snow tracking. We thank the late Lance Goodwin, Sian Williams, and Harry Penn of the Kluane Lake Research Station (AINA) for their assistance. We thank the Champagne and Aishihik First Nations and Kluane First Nation for supporting our work within their traditional territories. We thank the reviewers (especially B. Kolter) for their comments. This work was supported by the Natural Sciences and Engineering Research Council of Canada (NSERC). Funding Information: We thank the numerous assistants for help with the winter field work and hare monitoring and with laboratory sample preparation and analyses. We thank and recognize the late Peter Upton for his long-term contribution to the winter predator snow tracking. We thank the late Lance Goodwin, Sian Williams, and Harry Penn of the Kluane Lake Research Station (AINA) for their assistance. We thank the Champagne and Aishihik First Nations and Kluane First Nation for supporting our work within their traditional territories. We thank the reviewers (especially B. Kolter) for their comments. This work was supported by the Natural Sciences and Engineering Research Council of Canada (NSERC). Publisher Copyright: {\textcopyright} 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.",
year = "2021",
month = sep,
doi = "10.1007/s00442-021-05019-1",
language = "English",
volume = "197",
pages = "71--88",
journal = "Oecologia",
issn = "0029-8549",
publisher = "Springer",
number = "1",
}