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Dietary niche variation in an invasive omnivore: the effects of habitat and anthropogenic inputs on feral pig (Sus scrofa) resource use
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  • Michael S Peyton,
  • Kealohanuiopuna M Kinney,
  • Sarah Knox,
  • Grace Tredinnick,
  • Sara Hotchkiss
Michael S Peyton
University of Wisconsin-Madison

Corresponding Author:mspeyton@wisc.edu

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Kealohanuiopuna M Kinney
USDA Forest Service Institute of Pacific Islands Forestry
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Sarah Knox
USDA Forest Service Institute of Pacific Islands Forestry
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Grace Tredinnick
USDA Forest Service Institute of Pacific Islands Forestry
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Sara Hotchkiss
University of Wisconsin-Madison
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Abstract

Invasive omnivores may have profound impacts on ecological communities through diet selection, particularly when their functional roles differ from those in their native range. While the threat of feral pigs (Sus scrofa) to native plant communities in Hawai‘i are well known, their trophic dynamics and the drivers of variation in their diet remain understudied. We investigated the feral pig dietary niche on Hawai‘i Island using stable isotopes (13C and 15N) and Bayesian mixing models to identify drivers of variation in resource use. We also chronologically reconstructed diets for six subsampled individuals to understand temporal variation in resource use and individual diet specialization. Our results revealed feral pigs on Hawai‘i Island exhibit a broad dietary niche characterized by diverse diets, with substantial overlap in resource use across districts and habitats. Differences in dietary composition in the transition from forest to open habitat were driven primarily by an increasing reliance on human food subsidies in conjunction with a decreasing reliance on invertebrates, which may be partially driven by protein constraints on dietary composition. Pigs in forested areas largely displayed generalist feeding strategies, while those in open habitat tended to specialize, particularly on human food resources. Diets for chronologically subsampled individuals varied little, suggesting feral pig resource-use strategies in Hawai‘i tend to be stable through time. Individual niche-width was relatively narrow compared to that of feral pigs in Hawai‘i at large, indicating the relatively wide feral pig dietary niche is characterized by substantial intraspecific diet specialization, likely as a result of strong intraspecific competition. Understanding the drivers of feral pig resource use is crucial for informing management strategies aimed at mitigating their ecological impacts in imperiled systems like Hawai‘i.
08 Apr 2024Submitted to Ecology and Evolution
11 Apr 2024Submission Checks Completed
11 Apr 2024Assigned to Editor
05 Jun 2024Review(s) Completed, Editorial Evaluation Pending
05 Jun 2024Editorial Decision: Revise Minor
03 Sep 20241st Revision Received
07 Sep 2024Submission Checks Completed
07 Sep 2024Assigned to Editor
07 Sep 2024Review(s) Completed, Editorial Evaluation Pending
23 Sep 2024Editorial Decision: Accept