Differential migratory timing of western populations of Wilson's Warbler (Cardellina pusilla) revealed by mitochondrial DNA and stable isotopes

Abstract

ABSTRACT. Molecular markers and stable isotopes have provided important insights into the migratory connectivity of small landbirds. Research integrating these two methods has primarily focused on linking breeding and wintering sites, rather than focusing on timing of migratory movement of different breeding populations. We used mitochondrial DNA and isotopic markers to infer the timing of various breeding populations of migrating Wilson's Warblers (Cardellina pusilla) moving through a migratory stopover site, demonstrating the value of multiple sources of information in estimating the origin of migrants. Using mixed-stock analysis, we found that early spring migrants sampled in southwestern Arizona were dominated by warblers migrating to the West Coast of the contiguous United States, whereas later migrants included a large pulse of birds migrating to Alaska and western Canadian provinces. Stable hydrogen isotope data from individual birds showed the same timing pattern as genetic data. Had we used stabl...