Population trends of migratory landbirds along the Middle Rio Grande

Abstract

Using standardized mist-netting capture data from the Rio Grande Nature Center, Albuquerque, New Mexico from 1985-1994, and Breeding Bird Survey data from New Mexico and United States from 1980-1994, we compared local, regional, and national population trends of landbird species that migrate along the middle Rio Grande in fall. Evaluations of relationships among population trends, migratory distance, breeding habitat use, nest type, and foraging guilds revealed that population trends of Rio Grande migrants were relatively species-specific and that population changes were unequally distributed among habitats and life history groups. The fall banding data suggested that long-distance migrants, riparian forest migrants, canopy insectivores, and open-cup nesting species declined more over the 10-year period than other groups. Similarities between population trends from banding data and trends from Breeding Bird Survey increased as we expanded the geographic coverage of the Breeding Bird Survey data from New Mexico to the entire United States. We hypothesize that riparian habitat along the middle Rio Grande functions as a funnel that constricts habitat use during migration for species whose breeding and wintering populations are spread over broader geographic areas and that local population changes detected during mass migration may thus reflect widespread and large-scale changes.

Citation

Yong, Wang; Finch, Deborah M. 1997. Population trends of migratory landbirds along the Middle Rio Grande. The Southwestern Naturalist. 42(2): 137-147.