Stopover Ecology of Landbirds Migrating Along the Middle Rio Grande in Spring and Fall

摘要

This research represents the first comprehensive summary of our study of stopover ecology of migratory landbirds in riparian habitats along the middle Rio Grande of central New Mexico. We report results from mist-netting operations conducted during spring and fall migration in 1994, 1995, and 1996. A total of 23,800 individuals of 146 species were captured during the study. Of the 146 species, 53 percent were Neotropical migrants, and 32 percent were temperate migrants. The most abundant species were the MacGillivrays Warbler, Wilsons Warbler, and White-crowned Sparrow in spring and the Chipping Sparrow, Pine Siskin, and White-crowned Sparrow in fall. Migrants were most abundant between late April and the first 2 weeks of May in spring and between the last week of August and mid-October. Temperate migrants passed through the sites earlier in spring and later in fall than Neotropical migrants. About 50 percent of the birds had no visible fat stores upon capture. More birds used riparian habitat along the middle Rio Grande for stopover in fall than in spring. Species richness and relative abundance were lower in spring (108 species, 4,673 birds) than in fall (125 species, 19,127 birds).