Relative Importance of Nesting Habitat and Measures of Connectivity in Predicting the Occurrence of a Forest Songbird in Fragmented Landscapes

Avian Conservation and Ecology

Marie-Josée Fortin¹  Debbie Badzinski²  Stephanie Melles³  Kathryn Lindsay⁴ 

[1] Department of Ecology and Evolutionary Biology, University of Toronto;Ontario Program Manager Bird Studies Canada c/o Environment Canada;University of Toronto;Wildlife and Landscape Science Directorate, Environment Canada;

关键词: forest fragmentation;    graph-based network measures;    Hooded Warbler;    Setophaga citrina;    spatial graphs;   

DOI  :  10.5751/ACE-00530-070203

来源: DOAJ

【 摘 要 】

Theoretical and empirical studies suggest that well-connected networks of forest habitat facilitate animal movement and contribute to species' persistence and thereby the maintenance of biodiversity. Many structural and functional connectivity metrics have been proposed, e.g., distance to nearest neighboring patch or graph-based measures, but the relative importance of these measures in contrast to nesting habitat at fine spatial scales is not well established. With graph-based measures of connectivity, Euclidean distances between forest patches can be directly related to the preferred gap crossing distances of a bird (functional connectivity). We determined the relative predictive power of nesting habitat, forest cover, and structural or functional connectivity measures in describing the breeding distribution of Hooded Warblers (Setophaga citrina) over two successive breeding seasons in a region highly fragmented by agriculture in southern Ontario. Logistic regression models of nesting occurrence patterns were compared using Akaike's information criterion and relative effect sizes were compared using odds ratios. Our results provide support for the expectation that nest-site characteristics are indeed related to the breeding distribution of S. citrina. However, models based on nesting habitat alone were 4.7 times less likely than a model including functional connectivity as a predictor for the breeding distribution of S. citrina. Models of nest occurrence in relation to surrounding forest cover had lower model likelihoods than models that included graph-based functional connectivity, but these measures were highly confounded. Graph-based measures of connectivity explained more variation in nest occurrence than structural measures of forest connectivity, in both 2004 and 2005. These results suggest that S. citrina selected nesting areas that were functionally connected at their preferred gap crossing distances, but nesting habitat was a critically important predictor of nest occurrence patterns.

【 授权许可】

Unknown