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1 May 2011 The Gray Hawk (Buteo nitidus) is Two Species
Brian A. Millsap, Sergio H. Seipke, William S. Clark
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We compared the plumage, morphology, and the alarm call of two taxa of the Gray Hawk (Buteo nitidus) from north and south of a distributional gap in the species' range in Costa Rica. We found all age and sex classes completely distinguishable on the basis of several discrete plumage features. Three of four age and sex classes were diagnosably distinct by measurements of external morphology alone, and the two taxa had diagnosably different alarm calls. On the basis of the level and stability of morphological differentiation, and consistent with prior work suggesting substantial genetic differentiation between the two taxa, we recommend they be recognized as full species, B. nitidus, the Gray-lined Hawk, south of the distributional gap in Costa Rica, and B. plagiatus, the Gray Hawk, north of the gap.

© 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,
Brian A. Millsap, Sergio H. Seipke, and William S. Clark "The Gray Hawk (Buteo nitidus) is Two Species," The Condor 113(2), 326-339, (1 May 2011).
Received: 1 May 2010; Accepted: 1 December 2010; Published: 1 May 2011

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