Experimental moose reduction lowers wolf density and stops decline of endangered caribou
- Published
- Accepted
- Subject Areas
- Conservation Biology, Ecology, Natural Resource Management
- Keywords
- Rangifer tarandus, woodland caribou, moose, Canis lupus, apparent competition, adaptive management, endangered species, predation, conservation, Alces alces
- Copyright
- © 2017 Serrouya et al.
- Licence
- This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ Preprints) and either DOI or URL of the article must be cited.
- Cite this article
- 2017. Experimental moose reduction lowers wolf density and stops decline of endangered caribou. PeerJ Preprints 5:e3108v1 https://doi.org/10.7287/peerj.preprints.3108v1
Abstract
The expansion of moose into southern British Columbia caused the decline and extirpation of woodland caribou due to their shared predators, a process commonly referred to as apparent competition. Using an adaptive management experiment, we tested the hypothesis that reducing moose to historic levels would reduce apparent competition and therefor recover caribou populations. Nested within this broad hypothesis were three specific hypotheses: 1) sport hunting could be used to substantially reduce moose numbers to an ecological target; 2) wolves in this ecosystem were primarily limited by moose abundance; and 3) caribou were limited by wolf predation. These hypotheses were evaluated with a before-after control-impact (BACI) design that included response metrics such as population trends and vital rates of caribou, moose, and wolves. Three caribou subpopulations were subject to the moose reduction treatment and two were in a reference area where moose were not reduced. When the moose harvest was increased, the moose population declined substantially in the treatment area (by 70%) but not the reference area, suggesting that the policy had the desired effect and was not caused by a broader climatic process. Wolf numbers subsequently declined in the treatment area, with wolf dispersal rates 2.5 × greater, meaning that dispersal was the likely mechanism behind the wolf numerical response, though reduced recruitment and starvation was also documented in the treatment area. Caribou adult survival increased from 0.78 to 0.88 in the treatment area, but declined in the reference. Caribou recruitment was unaffected by the treatment. The largest caribou subpopulation stabilized in the treatment area, but declined in the reference area. The observed population stability is comparable to other studies that used intensive wolf control, but is insufficient to achieve recovery, suggesting that multiple limiting factors and corresponding management tools must be addressed simultaneously to achieve population growth.
Author Comment
This is a submission to PeerJ for review.