White-tailed Deer (Odocoileus virginianus) Subsidize Gray Wolves (Canis lupus) During a Moose (Alces americanus) Decline: A Case of Apparent Competition?

The Canadian Field-Naturalist

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Title White-tailed Deer (Odocoileus virginianus) Subsidize Gray Wolves (Canis lupus) During a Moose (Alces americanus) Decline: A Case of Apparent Competition?
Creator Barber-Meyer, Shannon M
Mech, L David
Subject Alces americanus; apparent competition; Canis lupus; diet; Gray Wolf; inverse-density-dependent predation; Min nesota; Moose; Odocoileus virginianus; scat; White-tailed Deer
Description Moose (Alces americanus) in northeastern Minnesota have declined by 55% since 2006. Although the cause is unresolved, some studies have suggested that Gray Wolves (Canis lupus) contributed to the decline. After the Moose decline, wolves could either decline or switch prey. To determine which occurred in our study area, we compared winter wolf counts and summer diet before and after the Moose decline. While wolf numbers in our study area nearly doubled from 23 in winter 2002 to an average of 41 during winters 2011–2013, calf:cow ratios (the number of calves per cow observed during winter surveys) in the wider Moose range more than halved from 0.93 in 2002 to an average of 0.31 during 2011–2013. Compared to summer 2002, wolves in summers 2011–2013 consumed fewer Moose and more White-tailed Deer (Odocoileus virginianus). While deer densities were similar during each period, average vulnerability, as reflected by winter severity, was greater during 2011–2013 than 2002, probably explaining the wolf increase. During the wolf increase Moose calves remained a summer food item. These findings suggest that in part of the Moose range, deer subsidized wolf numbers while wolves also preyed on Moose calves. This contributed to a Moose decline and is a possible case of apparent competition and inverse-density-dependent predation.
Publisher The Ottawa Field-Naturalists' Club
Date 2017-03-29
Type info:eu-repo/semantics/article

Format application/pdf
Identifier http://journals.sfu.ca/cfn/index.php/cfn/article/view/1924
Source The Canadian Field-Naturalist; Vol 130, No 4 (2016); 308-314
Language eng
Relation http://journals.sfu.ca/cfn/index.php/cfn/article/view/1924/1848
Rights Copyright (c) 2017 The Canadian Field-Naturalist

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