Avifauna of the Concho Valley of west-central Texas : with special reference to historical change

Abstract

Southwestern aridlands have undergone extensive changes in the broad pattern of vegetation since the mid-19th century. In West-Central Texas, woody plant species, primarily mesquite (Prosopis qlandulosa) and red-berry juniper (Juniperus pinchotii), dominated former grasslands by the mid-20th century. Field studies, from September 1975 to May 1978, were conducted to describe the avifauna and analyze the extent of avifaunal change in response to vegetation changes and other avian habitat alterations in the Concho Valley of Texas. Information was gathered on distribution, phenology, and local natural history of bird taxa. Avian community structure was quantitatively described in winter and breeding seasons for 8 study sites representing the major terrestrial vegetation types: riparian forest, bottom mesquite woodland, upland mesquite woodland, defoliated mesquite shrubland, juniper-1iveoak savannah, scrub oak shrubland, scrubby mesquite grassland, and grassland. Community descriptions included number of species, foraging guilds, species diversity (H', Shannon-Weiner index), density (birds per 40.4 hectares), and standing crop biomass (grams per 40.4 hectares). Historical records were examined to document changes that had occurred since mid-19th century in human population, agriculture, vegetation, and avifauna. ...