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1 February 2012 Response of Brown Creepers to Elevation and Forest Edges in the Southern Sierra Nevada, California
Kathryn L. Purcell, Craig M. Thompson, Douglas A. Drynan
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Abstract

We studied the responses of the Brown Creeper (Certhia americana) to forest edges in the southern Sierra Nevada, California. We censused birds and monitored nests in four forest types over an elevational gradient. We identified habitat patches homogeneous in terms of forest type, seral stage, and canopy cover and rated edges between adjoining patches as soft, moderate, or hard on the basis of relative differences in the suitability of adjacent patches. Brown Creepers were more abundant in sites with less high-contrast edge and more medium- and high-quality habitat. They avoided soft and moderate edges when selecting nest sites. Successful nests were in large-diameter trees and snags in forest with lower canopy closure and farther from moderate and hard edges than were unsuccessful nests. Clear negative responses to edge in terms of abundance, nest location, and nest survival were surprising because previous work has suggested that edge effects and the processes underlying them may differ in western coniferous forests because of their natural heterogeneity and because past forest management in the region resulted in fairly soft edges. The strength of the response was somewhat tied to the severity of the edge, although creepers avoided even soft edges. Hard edges were relatively rare and resulted primarily from natural discontinuities. Our results suggest that Brown Creepers should benefit from forest management that retains mature forest with minimal discontinuities, regardless of their source. Results also suggest that differences in relative habitat quality rather than differences in vegetation were responsible for observed patterns.

© 2012 by The Cooper Ornithological Society. All rights reserved. Please direct all requests for permission to photocopy or reproduce article content through the University of California Press's Rights and Permissions website, http://www.ucpressjournals.com/reprintInfo.asp.
Kathryn L. Purcell, Craig M. Thompson, and Douglas A. Drynan "Response of Brown Creepers to Elevation and Forest Edges in the Southern Sierra Nevada, California," The Condor 114(1), 185-196, (1 February 2012). https://doi.org/10.1525/cond.2012.100181
Received: 15 September 2010; Accepted: 1 September 2011; Published: 1 February 2012
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KEYWORDS
Brown Creeper
Certhia americana
contrast-weighted edge
edge effects
Elevational gradient
nest survival
snags
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