Blood may buy goodwill: no evidence for a positive relationship between legal culling and poaching in Wisconsin

Chapron & Treves [1] tested the hypothesis that allowing some lethal legal control reduces the level of poaching. Using an analysis of data from the wolf populations in Michigan and Wisconsin, they discounted this hypothesis, concluding: … ‘allowing wolf ( Canis lupus ) culling was substantially more likely to increase poaching than reduce it’ [1, p. 1]. However, the text and analysis have in my opinion severe shortcomings, including: (i) biased reporting of previously published results, (ii) the use of a statistical model to evaluate density dependence in wolf area use that does not have theoretical or empirical support, and (iii) a failure to evaluate how between-year variations in reproductive rates affect their conclusions. When variation in reproductive rates is taken into account in their analysis, the conclusion is the opposite—allowing wolf culling is more likely to decrease poaching than increase it.Chapron & Treves [1] cite, but seem to give a biased report of the findings from several published articles. They [1] claim that their analysis is the first to evaluate the relationship between legal culling and poaching in wolves. However, poaching of radio-tagged wolves has previously been shown to decrease in association with legal state culling in Wisconsin [2]. In the discussion they state: ‘As with prior studies on Wisconsin's wolf population [3], we did not detect any negative density dependence’ [1, p. 5]. However, the article they refer to does indeed find recruitment to be density-dependent. In addition, the occurrence of density dependence in wolf area use in Wisconsin is supported by a decrease in average wolf territory size as the population size increases [4]. Overall, it seems to me that results from the same study system that do not corroborate their own …