A quantitative analysis of winter distribution and habitats of Kirtland's Warblers in the Bahamas

Abstract

We compiled and analyzed 101 accessible reports of 194 individual Kirtland's Warblers (Dendroica kirtlandii) from the Bahama Archipelago, 1841-1997. Most individuals were reported from northern islands (88%), and most sight reports (84%) and specimen/banding records (76%) were on island groups that support or formerly supported open woodlands of Caribbean pine (Pinus caribaea). Where habitat descriptions were provided, 60% mentioned specifically pines or pine understory. After analyses for potential biases from misidentification in sight reports and unequal effort across islands, we found no evidence to support previous claims that Kirtland's Warblers prefer scrub or avoid pine habitats. Rather, based upon 1995-1997 winter surveys using acoustic broadcasts, Kirtland's Warblers were detected in pine woodlands of Abaco and Grand Bahama more frequently than expected compared to encounter rates generated by a null model of random habitat use. Two periods of apparent decline of the Kirtland's Warbler this century, and a modest population increase on the breeding grounds since 1990, occurred contemporaneously with degradation and recovery, respectively, of the fire-dependent pine ecosystem in the northern Bahamas. We recommend a rigorous re-evaluation of conservation priorities now premised largely upon breeding-season limitation.