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1 May 2011 Effects of Gypsy Moth Outbreaks on North American Woodpeckers
Walter D. Koenig, Eric L. Walters, Andrew M. Liebhold
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We examined the effects of the introduced gypsy moth (Lymantria dispar) on seven species of North American woodpeckers by matching spatially explicit data on gypsy moth outbreaks with data on breeding and wintering populations. In general, we detected modest effects during outbreaks: during the breeding season one species, the Red-headed Woodpecker (Melanerpes erythrocephalus), increased over pre-outbreak levels, while during the winter one species, the Yellow-bellied Sapsucker (Sphyrapicus varius), increased and one, the Downy Woodpecker (Picoides pubescens), decreased from pre-outbreak levels. Responses following outbreaks were similarly variable, and in general we were unsuccessful at predicting population responses to outbreaks from a priori knowledge of woodpecker ecology and behavior. We did, however, find evidence that the response of at least half of the species changed over the 34-year period covered by the study: except for the Northern Flicker (Colaptes auratus), whose response to outbreaks during the winter decreased, populations generally responded more positively to outbreaks with time. This temporal response suggests that North American woodpeckers may be taking greater advantage of the resource pulse and/or habitat changes caused by outbreaks of this exotic pest now than previously, so in the future the effects of gypsy moth outbreaks on these species may increase.

© 2011 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,
Walter D. Koenig, Eric L. Walters, and Andrew M. Liebhold "Effects of Gypsy Moth Outbreaks on North American Woodpeckers," The Condor 113(2), 352-361, (1 May 2011).
Received: 26 February 2010; Accepted: 1 January 2011; Published: 1 May 2011

cavity-nesting birds
gypsy moths
Lymantria dispar
pulsed resources
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