Article Abstract:
Structures of avian altitudinal distribution and ecological characteristics of the avifauna of the Sierra Madre del Sur were studied. Species richness was greatest at the two lowest altitudes and declined with increasing altitudes. Richness is relatively uniform within habitat types, but species turnover is rampant between habitat types. Habitat structure determines the avian altitudinal distribution, and interspecific competition has a weak effect. The modification and destruction of the habitat by humans also play an important role in avian altitudinal distribution patterns.
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Article Abstract:
The Mourning Warbler (Oporornis philadelphia) is highly variable throughout its breeding range. Its plumage, skeletal and external measurements follow a haphazard pattern of variation. Thus, evolutionary units are not apparent in this taxon. The Mourning Warbler does not conform to predictions based on Bergmann's rule. There seems to be no relationship between climatic and skeletal variables. Environmental selection does not play a role in shaping the pattern of breeding ground variability. These suggest an extensive gene flow between populations of this species.
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Article Abstract:
The geographic variation in coloration and morphology of Acorn Woodpeckers was investigated. One thousand five hundred and thirty-one study skins of Acorn Woodpeckers from 16 museum collections were studied with respect to locality, elevation above sea level, date of collection, iris color, sex and age. All measurements were made using the same set of calipers to ensure accuracy. Highly significant geographic differences in coloration and morphology were observed between the species.
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