Breeding Biology and Nesting Success of the Slate-Throated Whitestart (Myioborus miniatus) in Monteverde, Costa Rica

Abstract

Abstract I examined the breeding biology and nesting success of the Slate-throated Whitestart (Myioborus miniatus), a socially monogamous neotropical warbler, for five breeding seasons (2000–2004) in Monteverde, Costa Rica, near the center of its broad geographic range. Nesting was strongly seasonal, extending from late March through the end of June and coinciding with the end of the dry season and the onset of the rainy season in mid-May. Females constructed domed nests on open steep slopes or in banks along roads and trails. Mean clutch size was 2.9 eggs, and the mean incubation period was 14.2 days. Females performed all incubation of eggs and brooding of young nestlings, but both males and females fed nestlings and fledglings. Mean provisioning rate at nests when young were 5–9 days of age was 20.3 feedings/hr, and females fed young at a significantly higher rate than males (11.7 vs. 8.3 feedings/hr, respectively). Nestlings reached mean adult body mass of 9.5 g ∼ day 7–8, and mean age at fledging was...