BREEDING BIOLOGY OF FLORIDA PRAIRIE WARBLERS AND CUBAN YELLOW WARBLERS

We studied the breeding biology of the Florida Prairie Warbler (Dendroica discolor paludicola) and the Cuban Yellow Warbler (D. petechia gundlachi) in black mangrove (Avicennia germinans) habitats in the Florida Keys. A total of 42 Prairie and 20 Yellow warbler nests was located during 1990-1993. The breeding season for both species extended from late April through early July. The two species used a similar range of nest heights and placed their nests in similar locations within the mangroves, but Yellow Warbler nests averaged higher (1.77 m) than Prairie Warbler nests (1.60 m) and were less likely to be placed against mangrove trunks. Incubation periods averaged 12 days for both warblers Brooding periods averaged 11 days for Prairie Warblers and 12 days for Yellow Warblers. These periods are equivalent to or slightly longer than typical periods for other races of Prairie and Yellow Warblers that breed in North America, and similar to those for races of Yellow Warblers that breed in the West Indies. Mean clutch sizes for Prairie Warblers (2.50, N = 29) and for Yellow Warblers (2.50, N = 16) are smaller than those for temperate races of these warblers. Fledging success (number of young fledged/number of eggs laid) was higher for the Yellow Warbler (65.0%) than for the Prairie Warbler (45.8%), but the number of young fledged per nest did not differ significantly between the two species. Predation was the major cause of nest failure, accounting for approximately 64% of all egg losses.