Examining spatial patterns of selection and use for an altered predator guild
Anthropogenic disturbances have altered species’ distributions potentially impacting interspecific interactions. Interference competition is when one species denies a competing species access to a resource. One mechanism of interference competition is aggression, which can result in altered space-use of a subordinate species due to the threat of harm, otherwise known as a ‘landscape of fear’. Alternatively, subordinates might outcompete dominant species in resource-poor environments via a superior ability to extract resources. Our goal was to evaluate spatial predictions of the ‘landscape of fear’ hypothesis for a carnivore guild in Newfoundland, Canada, where coyotes recently immigrated. Native Newfoundland carnivores include red foxes, Canada lynx, and black bears. We predicted foxes and lynx would avoid coyotes because of their larger size and similar dietary niches. We used scat-detecting dogs and genetic techniques to locate and identify predator scats. We then built resource selection functions and tested for avoidance by incorporating predicted values of selection for the alternative species into the best supported models of each species. We found multiple negative relationships, but notably did not find avoidance by foxes of areas selected by coyotes. While we did find that lynx avoided coyotes, we also found a reciprocal relationship. The observed patterns suggest spatial partitioning and not coyote avoidance, although avoidance could still be occurring at different spatial or temporal scales. Furthermore, Newfoundland’s harsh climate and poor soils may swing the pendulum of interspecific interactions from interference competition to exploitative competition, where subordinates outcompete dominant competitors through a superior ability to extract resources.
KeywordsExploitative competition Interspecific competitive killing Intraguild predation Noninvasive sampling Molecular techniques
This study was funded by the Newfoundland and Labrador Department of Environment and Conservation (Sustainable Development and Strategic Science and the Institute for Biodiversity, Ecosystem Science and Sustainability) and the Safari Club International Foundation. We thank Colleen Soulliere, Robert Otto, Truman Porter, Steve Gullage, Tyler Hodder, Jason McGinn, Peter Tremblett, Frank Norman, Keith Lewis, Andrew Mouland and the Newfoundland and Labrador Department of Environment and Conservation (Sustainable Development and Strategic Science and the Institute for Biodiversity, Ecosystem Science and Sustainability) for field support. We thank Rachael Toldness, Andy Gygli, Matt Modlin and the Waits Lab Group, along with the Laboratory of Ecological, Evolutionary, and Conservation Genetics for laboratory support. We thank Dr. Anders Angerbjörn and three anonymous reviewers for their insightful comments and recommendations.
Author contribution statement
MAM conceived and designed experiment, completed lab work, and wrote manuscript. JDH assisted in project conception and design and manuscript preparation. LPW provided conceptual input and editorial comments. NDR assisted with field work and provided editorial advice. CJZ conducted field work and provided knowledge of species niche breadth. TKF and JFO provided editorial comments. SPM facilitated funding and reviewed manuscript.
Compliance with ethical standards
Statement of human and animal rights
Trained scat-detecting dogs were used to collect scats in this study and cared for in accordance with institutional and national guidelines. No animals or humans were used as research subjects in this article.
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