Despite conservation concern for the Swainson's Warbler (Limnothlypis swainsonii), little is known about its nonbreeding ecology. Because body condition can provide an indication of habitat quality, we examined Swainson's Warbler body condition indices in dry limestone forest and second growth scrub habitats in Jamaica, where this species was relatively common. In dry limestone forests, Swainson's Warblers showed no seasonal change in body mass corrected for structural size, furcular fat score, or age ratio. This contrasts with results from studies of other species of Neotropical migrant warblers that showed significant seasonal declines in body mass in similar xeric habitats. Dry limestone forest sites also supported a greater and less spatially variable biomass of prey commonly consumed by Swainson's Warblers than second growth scrub and shade coffee. Because Swainson's Warblers consume prey concealed beneath the leaf litter surface, they apparently are less susceptible to the extreme dry season desiccation that affects the availability of arthropods on the leaf litter surface and in the forest canopy. Swainson's Warbler density (0.6 birds/ha) and overwinter persistence (52%) also were relatively high in dry limestone forest sites, suggesting these forests provide high quality winter habitat for this species. Although Swainson's Warblers were able to increase body mass in preparation for migration in one second growth site, these disturbed habitats may vary in quality for Swainson's Warblers. Our results highlight the need for conservation of dry forests in the Greater Antilles as nonbreeding habitat for the Swainson's Warbler, as well as for numerous endemic species dependent upon these forests.