An Experimental Test of Competition among Mice, Chipmunks, and Squirrels in Deciduous Forest Fragments
An Experimental Test of Competition among Mice, Chipmunks, and Squirrels in Deciduous Forest Fragments
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DOI：
10.1371/journal.pone.0066798
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发表时间：
2013-06-18
期刊：
影响因子：
3.7
通讯作者：
Ostfeld, Richard S.
中科院分区：
文献类型：
--
作者：
Brunner, Jesse L.;Duerr, Shannon;Ostfeld, Richard S.
美国东北部的混合硬木林中生长着一群食料/杂食性啮齿类动物，包括灰松鼠（Sciurus carolinensis）、东部花栗鼠（Tamias striatus）和白足鼠（Peromyscus leucopus）。这些物种在地理上重合，在当地共同出现，消耗相似的食物资源。尽管它们对景观和斑块变量的特殊反应，斑块占用模型表明，竞争可能会影响它们各自的分布和丰度，从而影响它们对森林群落其他部分的影响。然而，缺乏实验研究。我们展示了一项大规模实验的结果，在这项实验中，我们从纽约达奇斯县小而孤立的森林碎片中取出白足鼠或灰松鼠，并将这些哺乳动物添加到其他碎片中，以改变这两个物种的丰度。然后，我们使用标记重新捕获分析来量化对常驻小鼠，松鼠和花栗鼠的种群水平和个体水平的影响。总的来说，我们几乎没有发现竞争的迹象。基本上没有对假定竞争者丰度变化的季节内数值反应。此外，虽然在某些模型中，个体水平的反应（表观生存和捕获概率）确实随着竞争对手密度的变化而变化，但这些影响通常可以用特定地点的参数来更好地解释，并且仅限于我们研究的19个地点中的少数几个。由于这三种常见的啮齿动物之间只有微弱的竞争或不存在竞争，我们预计它们的栖息地占用模式和种群动态在很大程度上是相互独立的。
Mixed hardwood forests of the northeast United States support a guild of granivorous/omnivorous rodents including gray squirrels (Sciurus carolinensis), eastern chipmunks (Tamias striatus), and white-footed mice (Peromyscus leucopus). These species coincide geographically, co-occur locally, and consume similar food resources. Despite their idiosyncratic responses to landscape and patch variables, patch occupancy models suggest that competition may influence their respective distributions and abundances, and accordingly their influence on the rest of the forest community. Experimental studies, however, are wanting. We present the result of a large-scale experiment in which we removed white-footed mice or gray squirrels from small, isolated forest fragments in Dutchess County, New York, and added these mammals to other fragments in order to alter the abundance of these two species. We then used mark-recapture analyses to quantify the population-level and individual-level effects on resident mice, squirrels, and chipmunks. Overall, we found little evidence of competition. There were essentially no within-season numerical responses to changes in the abundance of putative competitors. Moreover, while individual-level responses (apparent survival and capture probability) did vary with competitor densities in some models, these effects were often better explained by site-specific parameters and were restricted to few of the 19 sites we studied. With only weak or nonexistent competition among these three common rodent species, we expect their patterns of habitat occupancy and population dynamics to be largely independent of one another.