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Avian Community Organization and Habitat Structure

Willson, Mary F.
Ecology 1974 v.55 no.5 pp. 1017-1029
biomass, birds, body size, forests, grasslands, habitats, leaves, reproductive success, species diversity, trees, vegetation cover
Bird species diversity was linearly correlated with foliage height diversity and curvilinearly with total percent vegetation cover. The addition of trees in a vegetational series has a disproportionate effect on the addition of species, primarily by the addition rather than the expansion of guilds. No basic relationship of species—packing within guilds is associated with bill or body size except frequently within two—member guilds. Estimated abundance and biomass of birds does not appear to be related to productivity of the habitats, in contrast to reports form the literature. Similarity of bird species composition is not related to similarity of foilage distribution, when like study areas are compared. Avifaunas of grasslands generally differed more among themselves than did those of forests. Bird species overlaps were correlated with foilage height overlaps only for part of the variational range for two— and three—layered habitats, and little if at all for grasslands. Width of "habitat—niche" is not related to numerical dominance, taxonomic or ecological categories. Because many of these results do not coincide with previous attempts at ecological generalization, great care in such attempts seems strongly indicated. Studies should be made of meticulously delineated subcommunities, resource measurement, and reproductive success, as well as events in the nonbreeding season.