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Geographic Variation in the Yellow-Billed Cacique, Amblycercus holosericeus, a Partial Bamboo Specialist
Andrew W. Kratter
Vol. 95, No. 3 (Aug., 1993), pp. 641-651
Published by: American Ornithological Society
Stable URL: http://www.jstor.org/stable/1369607
Page Count: 11
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Geographic variation in the Yellow-billed Cacique (Amblycercus holosericeus) was examined to determine whether bamboo-specialized populations in highland Costa Rica and the Andes are more phenetically similar to one another than to lowland populations not specialized on bamboo. Significant geographic variation was found for all mensural characters; in general, characters varied in accordance with Bergmann's rule. Specimens largely separated into two groups: (1) the Andes and (2) Middle America and the Chocó forests of northwestern South America. The bamboo-specialized population of highland Costa Rica grouped with the non-specialized lowland samples of group 2, not with specialists in the Andes. This suggests that bamboo specialization arose independently in these two populations. There is no convergence in morphology evident between the two populations specialized on bamboo; thus specialization on bamboo as a foraging site or habitat may not be associated with morphological specialization in this species.
The Condor © 1993 Cooper Ornithological Society