The enemy of my enemy is my friend : Native pine marten recovery reverses the decline of the red squirrel by suppressing grey squirrel populations

Sheehy, Emma and Sutherland, Chris and O’Reilly, Catherine and Lambin, Xavier (2018) The enemy of my enemy is my friend : Native pine marten recovery reverses the decline of the red squirrel by suppressing grey squirrel populations. Proceedings of the Royal Society B: Biological Sciences, 285 (1874). ISSN 0962-8452

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Shared enemies may instigate or modify competitive interactions between species. The dis-equilibrium caused by non-native species introductions has revealed that the outcome of such indirect interactions can often be dramatic. However, studies of enemy-mediated competition mostly consider the impact of a single enemy, despite species being embedded in complex networks of interactions. Here, we demonstrate that native red and invasive grey squirrels in Britain, two terrestrial species linked by resource and disease-mediated apparent competition, are also now linked by a second enemy-mediated relationship involving a shared native predator recovering from historical persecution, the European pine marten. Through combining spatial capture–recapture techniques to estimate pine marten density, and squirrel site-occupancy data, we find that the impact of exposure to predation is highly asymmetrical, with non-native grey squirrel occupancy strongly negatively affected by exposure to pine martens. By contrast, exposure to pine marten predation has an indirect positive effect on red squirrel populations. Pine marten predation thus reverses the welldocumented outcome of resource and apparent competition between red and grey squirrels.

Item Type: Article
Additional Information: Funding Information: We declare we have no competing interests. Funding. The research leading to these results has received funding from the Irish Research Council and from the People Programme (Marie Curie Actions) of the European Union’s Seventh Framework Programme (FP7/2007-2013) under REA grant agreement no. 291760 ELEVATE, and Forestry Commission Scotland. We thank Forest Enterprise Scotland and Trees for Life for support. Thanks also to the ScottishWildlife Trust, E. Schulte, B. Priestly, K. Kortland, A. Jarrott, D. Anderson, T. Lightly, I. Cepukaite, S. Eastwood, M. Oliver, L. Currie, R. Greenwood, P. Whyatt, M. Hawkins, G. Neill, S. Willis, G. Stewart, I. Wilkinson, T. Ferrie, Luss Estates, Penicuik Estate, East andWest Dunbartonshire Councils, Ballikinrain School and Dawyck Botanic Gardens. Publisher Copyright: © 2018 The Authors.
Uncontrolled Keywords: /dk/atira/pure/subjectarea/asjc/2400
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Date Deposited: 19 Oct 2022 23:02
Last Modified: 15 Aug 2023 02:30

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