Species abundances, guild dominance patterns, and community structure of breeding riparian birds

Abstract

I investigated trends in bird species populations, guild structure, and bird communities along a riparian altitudinal cline in the Medicine Bow National Forest of southeastern Wyoming. Streamside habitats were divided into three elevational zones: low-elevation (2050 to 2260 m) cottonwood zone, mid-elevation (2290 to 2530 m) mixed shrub willow zone, and high elevation (2590 to 2990 m) subalpine willow zone. Vegetational complexity decreased from low to high zones, with loss of vertical habitat layers and increased foliage density and dominance of dwarf willows. Ground and lower-canopy foragers dominated all three zones, but upper-eanopy foragers, aerial foragers, and bark foragers declined in numbers with increased elevation, altogether disappearing in the subalpine zone. Highest similarities within foraging guilds were between low- and mid-elevation zones, whereas fewest guild species were shared between low and high-elevation zones. Trends in avian numbers were explained by relating guild occupancy patterns to the presence or absence of habitat layers in each elevational zone. Greater habitat stratification in low-elevation cottonwood communities resulted in greater capability to support avian species.

Citation

Finch, Deborah M. 1989. Species abundances, guild dominance patterns, and community structure of breeding riparian birds. In: Sharitz, R.R.; Gibbons, J.W., eds. Freshwater Wetlands and Wildlife: Proceedings of a Symposium Held at Charleston, South Carolina; March 24-27, 1986; CONF-860S101. DOE Symposium Series 61. Oak Ridge,TN: U.S. Department of Energy, Office of Scientific and Technical Information. p. 629-645.