Predator persistence in fragmented forests: lynx and snowshoe hares

濒危物种面临的主要威胁之一是栖息地的丧失。在森林中，这种损失通常会使原始森林的残留林被年龄或物种组成不同的其他林分包围。对于森林哺乳动物，这些不同林分类型的复杂马赛克强烈影响种群动态；对于一些物种，种群随着栖息地碎片化的发生而下降。通常，森林中的捕食者和猎物会在不同的空间尺度上对碎片化做出反应，猎物停留在特定的林木林中，捕食者在林木之间移动。随着栖息地的丧失，以及猎物可以使用的林分变得更小或更远，捕食者可能无法获得足够的猎物来生存，因为带着猎物在林间旅行的成本变得太高。我感兴趣的是森林哺乳动物对森林碎片化的反应，我的主要研究目标是解释随着景观变得越来越碎片化，捕食者和猎物的相互作用是如何改变的。不同林分类型中猎物的种群动态将在很大程度上决定它们的捕食者能否在支离破碎的景观中生存下来。在一个极端，猎物可能只使用少数相距较远的林分；在另一个极端，它们可能发生在大多数林分中。作为一个模型系统，我将重点放在蒙大拿州西部的雪鞋野兔(Lepus Americanus)和加拿大山猫(Lynx Candensis)上。我正在描述不同林分类型的野兔的密度、存活率和繁殖力。然后，我在探索哪种类型的山猫用来狩猎，它们在两次捕杀之间旅行的距离有多远，以及它们的食物中有多大比例是这一地区的野兔。我正在将这些结果统一到空间模型中，这样我就可以对改变不同类型栖息地的数量对这些物种的影响进行建模。这项研究计划将促进我们对捕食者和猎物如何应对森林碎片化的总体理解，以及预测可能有助于保留景观中物种的剩余森林林分的配置。

One of the major threats to imperiled species is the loss of habitat. In forests, this loss often leaves remnant stands of the original forest surrounded by other stands that differ in age or species composition. For forest mammals, these complex mosaics of different stand types strongly affect population dynamics; for some species, populations decline as habitat fragmentation occurs. Often, predators and prey in forests will respond to fragmentation at different spatial scales, with prey staying in particular forest stands and predators moving among stands. As habitat loss occurs and the stands that prey can use become smaller or farther apart, predators may not be able to obtain enough prey to survive because the cost of traveling among the stands with prey becomes too high. I am interested in how forest mammals respond to forest fragmentation, and my main research objective is to explain how predator-prey interactions are changed as a landscape becomes increasingly fragmented. The population dynamics of prey in different stand types will largely determine whether their predators can persist in a fragmented landscape. At one extreme, prey might use only a few, far apart stands; at the other extreme, they might occur in the majority of stands. As a model system, I am focusing on snowshoe hares (Lepus americanus) and Canada lynx (Lynx canadensis) in western Montana. I am characterizing density, survival, and reproduction of hares in different stand types. I am then exploring which stand types lynx use for hunting, how far they travel between kills, and what proportion of their diet consists of hares in this region. I am unifying these results in spatial models so that I can model the effects of changing the amount of different types of habitat on these species. This research program will advance our general understanding of how predators and prey respond to forest fragmentation, as well as predicting configurations of remaining forest stands that might help to retain species in the landscape.