Epizootic of beak deformities among wild birds in Alaska: An emerging disease in North America?

The Auk
By: , and 



The sudden appearance of a large cluster of animals with gross abnormalities may signal a significant change in an ecosystem. We describe an unusual concentration of beak deformities that appear to have arisen rapidly within Alaska and now extend southward along the Pacific Coast. In Alaska we have documented 2,160 Black-capped Chickadees (Poecile atricapillus) and 435 individuals of 29 other species of birds, primarily during the past decade, with grossly overgrown and often crossed beaks. The annual prevalence of beak abnormalities among adult Black-capped Chickadees in south-central Alaska varied from 3.6% to 9.7% and averaged 6.5 ± 0.5% between 1999 and 2008. Only 0.05 ± 0.05% of nestlings and 0.3 ± 0.2% of juveniles <6 months old had abnormal beaks, which suggests that this is either a latent developmental or an acquired condition. We documented 80 cases in which a Black-capped Chickadee captured with an apparently normal beak was subsequently recaptured with a beak abnormality and 8 cases in which a beak deformity was no longer detectable upon recapture. Necropsy and histopathology of a sample of affected individuals provided no conclusive evidence of the etiology of this condition. Deformities appear to affect primarily the keratin layer of the beak and may result from abnormally rapid growth of the rhamphotheca. Some affected birds also exhibited lesions in other keratinized tissues of the skin, legs, feet, claws, and feathers, which may represent a systemic disorder or secondary conditions. Additional studies are currently underway to determine diagnostic signs and the underlying cause of this avian keratin disorder.

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Publication type Article
Publication Subtype Journal Article
Title Epizootic of beak deformities among wild birds in Alaska: An emerging disease in North America?
Series title The Auk
DOI 10.1525/auk.2010.10111
Volume 127
Issue 4
Year Published 2010
Language English
Publisher American Ornithological Society
Contributing office(s) Alaska Science Center, National Wildlife Health Center
Description 17 p.
First page 882
Last page 898
Country United States
State Alaska
Online Only (Y/N) N
Additional Online Files (Y/N) N
Google Analytic Metrics Metrics page
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