Autumn stopover ecology of the Blackpoll Warbler (Dendroica striata) in thorn scrub forest of the Dominican Republic

Abstract

We used mist-netting, color-banding, resighting, and behavioral observations to study the autumn stopover ecology of migrating Blackpoll Warblers (Dendroica striata) in coastal thorn scrub forest in the area of Cabo Rojo, Pedernales Province, Dominican Republic. Blackpoll Warblers were the most abundant migrant present in this habitat throughout most of October 1997. Warblers stopping over in this habitat were generally young with moderate to large fat stores. No lean birds (fat score = 0) were captured. Our behavioral observations suggest that Blackpoll Warblers are flexible in terms of social organization, with birds associating in single-species flocks and in mixed-species aggregations, but single birds were also recorded. Foraging activity consisted primarily of gleaning from leaves and was focused on lepidopteran larvae, whose high abundance coincided with Blackpoll Warbler arrival. We suggest that most stopover Blackpoll Warblers were not weakened individuals searching for emergency energy stores but were forced down owing to unfavorable weather conditions for migration; others may have been taking advantage of landfall on the south coast of Hispaniola for daytime rest before continuing across the Caribbean Sea to South America. Coastal thorn scrub forest of Hispaniola appears to be a preferred stopover habitat for a variety of migrants, providing a place to rest and replenish energy reserves following transoceanic flight.