Compositional aspects of breeding avifaunas in selected woodlands of the southern Guadalupe Mountains, Texas
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1975
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Abstract
Field studies were conducted in the summers of 1972, 1973, and 1974, to quantitatively document the breeding avifaunas of 5 relict woodland communities of the southern Guadalupe Mountains, Guadalupe Mountains National Park, Texas. Study plots, ranging in size from 20 acres (8.1 ha) to 30 acres (12.1 ha), were established one each in Main McKittrick Canyon -- elevation 5100 feet (1554 m), North McKittrick Canyon -- elevation 5300 feet (1615 m), South McKittrick Canyon -- elevation 5250 feet (1600 m), Upper Dog Canyon -- elevation 6500 feet (1981 m), and the Bowl -- elevation 7850 feet (2393 m). Deciduous trees (Quercus undulata, Quercus muhlenbergia, Acer grandidentatum) were the dominant vegetation in the 4 canyons. Conifers (Pinus flexilis, Pinus ponderosa, Pseudotsuga menziesii) were the dominant vegetation in the Bowl. Species diversity (Shannon-Weiner index) of the breeding avifaunas ranged from a low of 2.83 for North McKittrick Canyon in 1973 to a high of 3.43 for Upper Dog Canyon in 1974. Upper Dog Canyon supported the greatest species diversity each of the 3 years of the study. The least fluctuation from year to year in species diversity occurred in the Bowl. Total breeding species present in any one season ranged from a low of 20 for North McKittrick Canyon in 1973 to a high of 38 for Upper Dog Canyon in 1974. Fifty-six species were documented as breeding in the combined study areas. Density, recorded as breeding birds per 100 acres (40.47 ha), ranged from a low of 206.6 for Main McKittrick Canyon in 1973 to a high of 459.4 for Upper Dog Canyon in 1974. Fluctuations in breeding bird density were slight in the Bowl and Upper Dog Canyon on a year to year basis. A greater density fluctuation occurred in the lower canyons. ...
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Major wildlife and fisheries sciences