Stable isotope evidence links breeding geography and migration timing in wood warblers (Parulidae)

Abstract

Tracking seasonal movements of songbirds is a key step in understanding the annual cycle of migrants. To be er understand autumn migration of wood warblers, I analyzed stable-hydrogen isotope ratios of feathers collected from three species captured during stopover at the Bosque del Apache National Wildlife Refuge, New Mexico. To assess the form and strength of the relationship between timing of migration and breeding origins, I regressed stable-hydrogen isotope ratios of feathers against date of capture. These analyses indicated that Orange-crowned Warblers (Vermivora celata) and Common Yellowthroats (Geothlypis trichas) breeding in the southern portion of these species’ ranges precede their northern conspecifi cs in autumn migration. By contrast, Yellow Warblers (Dendroica petechia) from northern breeding sites arrived before more southerly breeding conspecifi cs. This pa ern is similar to that reported previously in Wilson’s Warbler (Wilsonia pusilla). These fi ndings suggest that, among wood warblers, (1) timing of autumn migration is o en strongly related to breeding location and (2) interspecifi c variation in the direction of this relationship is large. The direction and strength of these pa erns have implications for our understanding of inter- and intraspecifi c geographic variation in the life histories of migrants.

Citation

Kelly, Jeffrey F. 2006. Stable isotope evidence links breeding geography and migration timing in wood warblers (Parulidae). The Auk. 123(2): 431-437.