干旱区生态环境知识资源中心

Wintering Prairie Warblers (Dendroica discolor) were studied in pine forest, desert them scrub, and desert wash habitats of the Sierra do Bahoruco, Dominican Republic from October-April 1996-1998 and January-February 1999. We used mist netting, color banding., and extensive resighting of color-banded birds to quantify habitat-specific demographics, site fidelity, and fitness indices. Males predominated early in the season in pine habitat while females predominated in the desert. Sex ratios were more equal through the drier months of late winter although females continued to be more frequent in the desert. Adult birds predominated throughout all habitats and time periods. Nonterritorial wanderers were far more common in desert habitats than in pine forest, and females predominated among these wanderers. Site persistence was moderately high, but variable between habitats and time periods, and was significantly lower in the drier months in thorn scrub than it was in the desert wash or pine forest. Annual return rates were generally high and did not vary significantly among years. Birds showed significant declines in pectoral-muscle-mass scores in both of the desert habitats but not in the pine forest. Data presented here emphasize the importance of dry-season events and habitat heterogeneity in the winter ecology of migratory birds.