Kirtland's Warblers in anthropogenically disturbed early-successional habitats on Eleuthera, the Bahamas

Abstract

To characterize the nonbreeding habitat of Kirtland's Warbler (Dendroica kirtlandii) on Eleuthera, The Bahamas, we quantified the habitat at sites where we captured the Warblers and compared these traits with those of random sites and sites of tall coppice. On the basis of a chronosequence of satellite imagery, 153 capture sites ranged in age from 3 to 28 years after human disturbance, mean 14.6 years ± 6.3 (SD). Capture sites had been abandoned after clearing (65%), converted to goat pasture (26%), burned (2%), or were young second growth following unknown disturbance (7%). Canopies in 104 capture plots were lower (mean 1.8 m) than canopies in random plots (mean 2.7 m) and plots of late-successional tall coppice (mean 6.3 m). At seven sites mean foliage density in capture plots was consistently greatest at 0.5 to 1.0 m height, but the sites were heterogeneous for other foliage-height classes <3 m and for time since disturbance, canopy height, stem density, and five ground-cover traits. Plots did not differ by the sex of the captured bird except for a difference (P = 0.05) in foliage density at heights <3 m. Kirtland's Warblers frequently consumed fruit (69% of 499 observations), especially from Lantana involucrata, Erithalis fruticosa, and Chiococca alba. Foliage of these plants was more abundant in capture plots than random plots. Because the Warblers consume fruit extensively and fruit is more abundant in early successional habitat, this species, like other nearctic-neotropical migrants that breed in early successional habitats, is absent from mature forests on the wintering grounds. © The Cooper Ornithological Society 2010.