Tree Swallow (Tachycineta bicolor)
The research (linked here) revealed that stable hydrogen isotopes were indicative of the latitude of molting sites and strontium was linked to the longitude of geological features found in proximity to the area where feathers were grown. Taken together, modeling revealed that, “these isotopes have the potential to provide predictable and complementary markers for estimating long-distance animal movements.”
GRAPHIC: Geographic variation of (a) dD and (b) 87Sr/86Sr values in Tree Swallow feathers. Contour maps were produced by ordinary kriging and are based on mean values in primary flight feathers at 18 breeding sites (denoted by black circles).
Megan J. Sellick, T. Kurt Kyser, Michael B. Wunder, Don Chipley, D. Ryan Norris (2009). Geographic Variation of Strontium and Hydrogen Isotopes in Avian Tissue: Implications for Tracking Migration and Dispersal PLoS ONE, 4 (3) DOI: 10.1371/journal.pone.0004735