, Volume 17, Issue 6, pp 569-586

The influence of research scale on bald eagle habitat selection along the lower Hudson River, New York (USA)

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Abstract

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.

This revised version was published online in May 2005 with corrections to the Cover Date.