Ribic Christine A, Donner Deahn M, Beck Albert J, Rugg David J, Reinecke Sue, Eklund Dan
US Geological Survey, Wisconsin Cooperative Wildlife Research Unit, University of Wisconsin, Madison, Wisconsin, United States of America.
Institute for Applied Ecosystem Studies, Northern Research Station, US Forest Service, Rhinelander, Wisconsin, United States of America.
PLoS One. 2017 Jan 12;12(1):e0170099. doi: 10.1371/journal.pone.0170099. eCollection 2017.
The North American beaver (Castor canadensis) is a managed species in the United States. In northern Wisconsin, as part of the state-wide beaver management program, the Chequamegon-Nicolet National Forest removes beavers from targeted trout streams on U.S. Forest Service lands. However, the success of this management program has not been evaluated. Targeted removals comprise only 3% of the annual beaver harvest, a level of effort that may not affect the beaver population. We used colony location data along Forest streams from 1987-2013 (Nicolet, northeast Wisconsin) and 1997-2013 (Chequamegon, northwest Wisconsin) to assess trends in beaver colony density on targeted trout streams compared to non-targeted streams. On the Chequamegon, colony density on non-targeted trout and non-trout streams did not change over time, while colony density on targeted trout streams declined and then stabilized. On the Nicolet, beaver colony density decreased on both non-targeted streams and targeted trout streams. However, colony density on targeted trout streams declined faster. The impact of targeted trapping was similar across the two sides of the Forest (60% reduction relative to non-targeted trout streams). Exploratory analyses of weather influences found that very dry conditions and severe winters were associated with transient reductions in beaver colony density on non-targeted streams on both sides of the Forest. Our findings may help land management agencies weigh more finely calibrated beaver control measures against continued large-scale removal programs.
北美河狸（Castor canadensis）在美国是一种受管理的物种。在威斯康星州北部，作为全州河狸管理计划的一部分，奇科梅戈-尼科莱特国家森林在联邦林业局所属土地上，将河狸从目标鳟鱼溪流中移除。然而，该管理计划的成效尚未得到评估。目标移除仅占河狸年度捕获量的3%，这一努力程度可能不会对河狸种群产生影响。我们利用1987 - 2013年（尼科莱特，威斯康星州东北部）和1997 - 2013年（奇科梅戈，威斯康星州西北部）森林溪流沿线的栖息地位置数据，评估目标鳟鱼溪流与非目标溪流相比河狸栖息地密度的变化趋势。在奇科梅戈地区，非目标鳟鱼溪流和非鳟鱼溪流的栖息地密度没有随时间变化，而目标鳟鱼溪流的栖息地密度先下降然后趋于稳定。在尼科莱特地区，非目标溪流和目标鳟鱼溪流的河狸栖息地密度均下降。然而，目标鳟鱼溪流的栖息地密度下降得更快。在森林两侧，目标诱捕的影响相似（相对于非目标鳟鱼溪流减少了60%）。对天气影响的探索性分析发现，非常干燥的条件和严冬与森林两侧非目标溪流河狸栖息地密度的短暂下降有关。我们的研究结果可能有助于土地管理机构在持续的大规模移除计划与更精细校准的河狸控制措施之间进行权衡。
