The influence of research scale on bald eagle habitat selection along the lower Hudson River, New York (USA)
The influence of research scale on bald eagle habitat selection along the lower Hudson River, New York (USA)
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研究规模对哈德逊河下游秃鹰栖息地选择的影响，纽约（美国）
作者：
C. Thompson;K. McGarigal
随着景观生态学的概念被融入到其他学科中，空间格局对动物丰度和分布的影响引起了人们的极大关注。然而，景观生态学理论和技术在野生动物研究中的应用还存在很大差距。通过将景观生态学技术与传统的野生动物栖息地分析方法相结合，我们为美国纽约哈德逊河沿岸的秃头鹰(Haliaetus Leucocephalus)的繁殖定义了一个以生物为中心的视角。在1999年和2000年的繁殖季节，我们对四对繁殖的鹰进行了密集的监测，并收集了详细的栖息地和饲料位置的信息。我们的分析集中在三个关键的栖息地元素：可用的栖息树，进入觅食区域，以及不受人类干扰。我们假设，相对于这些元素中的每一个，鹰的栖息地选择会随着分析的空间尺度而变化，这些比例关系也会随着栖息地元素的不同而变化。我们考察了空间尺度的两个要素：颗粒和局部范围。颗粒被定义为最小映射单元；局部范围被定义为围绕每个焦点放置的分析窗口的大小。对于每个生境元素，我们量化了不同空间尺度上的栖息地利用。鹰的栖息地利用表现出与所有栖息地特征相关的尺度依赖的格局，包括多尺度和阈值状格局。这一信息支持野生动物栖息地利用中存在规模依赖关系，并允许对哈德逊河繁殖鹰栖息地进行更准确和生物相关的评估。
As the concepts of landscape ecology have been incorporated into otherdisciplines, the influence of spatial patterns on animal abundance anddistribution has attracted considerable attention. However, there remains asignificant gap in the application of landscape ecology theories and techniquesto wildlife research. By combining landscape ecology techniques withtraditionalwildlife habitat analysis methods, we defined an ‘organism-centeredperspective’for breeding bald eagles (Haliaeetus leucocephalus) alongthe Hudson River, New York, USA. We intensively monitored four pairs ofbreedingeagles during the 1999 and 2000 breeding seasons, and collected detailedinformation on perch and forage locations. Our analysis focused on threecritical habitat elements: available perch trees, access to foraging areas, andfreedom from human disturbance. We hypothesized that eagle habitat selectionrelative to each of these elementswould vary with the spatial scale of analysis, and that these scalingrelationships would vary among habitat elements. We investigated two elementsofspatial scale: grain and local extent. Grain was defined as the minimum mappingunit; local extent was defined by the size of an analysis window placed aroundeach focal point. For each habitat element, we quantified habitat use over arange of spatial scales. Eagles displayed scale-dependent patterns of habitatuse in relation to all habitat features, including multi-scale andthreshold-like patterns. This information supports the existence ofscale-dependant relationships in wildlife habitat use and allowed for a moreaccurate and biologically relevant evaluation of Hudson River breeding eagle habitat.