Ovenbirds (Seiurus aurocapillus) and Swainson's Warblers (Limnothlypis swainsonii) wintering in Jamaica exhibited divergent foraging behaviors, with Ovenbirds picking prey from the leaf litter surface and Swainson's Warblers flicking leaves aside to search for prey concealed beneath the leaf litter. The two species consumed significantly different prey: Ovenbirds feeding primarily on ants, and Swainson's Warblers most frequently consuming beetles and spiders, but also consuming roaches and small geckos. The differences in foraging strategies help explain the species' different habitat use patterns. Because of the ubiquity of ants, Ovenbirds are habitat generalists whereas Swainson's Warblers are dependent on habitats that have a well-developed canopy, leaf litter layer, and an abundant leaf litter fauna Ovenbird body condition declined seasonally, concurrent with seasonal declines in prey biomass. Rectrix regrowth rates and overwinter change in body mass were significantly correlated with ant biomass on Ovenbird territories. In habitats and years in which prey biomass decreased to <2.5 mg/0.25 m 2, Ovenbirds were not able to maintain body mass. The results confirm the hypothesis that dry season desiccation significantly decreases arthropod populations and the severity of the dry season strongly affects habitat quality for Ovenbirds Swainson's Warblers appear to be more tolerant of dry season leaf litter desiccation than Ovenbirds, as habitats with a deep leaf litter layer provided refugia for invertebrates. Correspondingly, Swainson's Warbler showed no seasonal decline in dry forests where they were relatively common. These results underscore the need for conservation of dry forests for the geographically restricted Swainson's Warblers Ovenbirds defended spatiotemporal territories, such that home ranges of neighboring birds overlapped, but individuals were not in the same place at the same time. Home range size was not significantly correlated with prey biomass. However, I experimentally decreased ant biomass on portions of the home ranges of four individuals. These birds showed a significant increase in home range size and movement rates. Control birds showed no change in either variable. These results strongly suggest that Ovenbirds constantly monitor food resources and adjust home range size accordingly and that food abundance limits winter habitat carrying capacity / acase@tulane.edu
| Identifer | oai:union.ndltd.org:TULANE/oai:http://digitallibrary.tulane.edu/:tulane_26113 |
| Date | January 1999 |
| Contributors | Strong, Allan M (Author), Sherry, Thomas W (Thesis advisor) |
| Publisher | Tulane University |
| Source Sets | Tulane University |
| Language | English |
| Detected Language | English |
| Rights | Access requires a license to the Dissertations and Theses (ProQuest) database., Copyright is in accordance with U.S. Copyright law |
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