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Temporal variation in translocated Isle Royale wolf diet reflects optimal foraging.
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  • Adia Sovie,
  • Mark Romanski,
  • Elizabeth Orning,
  • David Mareweck,
  • Rachel Nichols,
  • Seth Moore,
  • Jerrold Belant
Adia Sovie
Michigan State University

Corresponding Author:[email protected]

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Mark Romanski
Isle Royale National Park
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Elizabeth Orning
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David Mareweck
Conservation Alpha
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Rachel Nichols
Grand Portage Band of Lake Superior Chippewa
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Seth Moore
Grand Portage Band of Lake Superior Chippewa
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Jerrold Belant
Michigan State University
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Wolves (Canis lupus) can exert top-down pressure and shape ecological communities through selective predation of ungulates and beavers (Castor Canadensis). Considering their ability to shape communities through predation, understanding wolf foraging decisions is critical to predicting their ecosystem level effects. Specifically, if wolves are optimal foragers, consumers that optimize tradeoffs between cost and benefits of prey acquisition, changes in these factors may lead to prey switching or negative-density dependent selection with potential consequences for community stability. For wolves, factors affecting cost and benefits include prey vulnerability, risk, reward, and availability which can vary temporally. We described wolf diet in by frequency of occurrence and percent biomass and characterized diet in relation to optimal foraging using prey remains found in wolf scats on Isle Royale National Park, Michigan, USA during May–October 2019–2020. We used logistic regression to estimate prey consumption over time. We predicted prey with temporal variation in cost (vulnerability and/or availability) such as adult and calf moose (Alces alces) and beaver to vary in wolves’ diet. We analyzed 206 scats and identified 62% of remains as beaver, 26% as and moose, and 12% as other (birds, smaller mammals, and wolves). Adult moose were more likely to occur in wolf scat in May, when moose are in poor condition following winter. Similarly, the occurrence of moose calves peaked June–mid July following parturition but before their vulnerability declined as they matured. In contrast, beaver occurrence in wolf scat did not change over time, possibly reflecting the importance of low handling cost prey items for recently introduced lone or paired wolves. Our results demonstrate that wolf diet is plastic and responsive to temporal changes in prey acquisition cost as predicted by optimal foraging theory. Temporal fluctuation in diet may influence wolves’ ecological role if prey respond to increased predation risk by altering their foraging or breeding behavior.
23 Aug 2022Submitted to Ecology and Evolution
24 Aug 2022Submission Checks Completed
24 Aug 2022Assigned to Editor
26 Sep 2022Reviewer(s) Assigned
13 Dec 2022Review(s) Completed, Editorial Evaluation Pending
13 Dec 2022Editorial Decision: Revise Minor
08 Feb 20231st Revision Received
09 Feb 2023Submission Checks Completed
09 Feb 2023Assigned to Editor
09 Feb 2023Review(s) Completed, Editorial Evaluation Pending
15 Feb 2023Editorial Decision: Accept