Hobson, K.A., Van Wilgenburg, S., Wassenaar, L.I., Moore, F., and Farrington J. 2007. Estimating origins of three species of Neotropical migrant songbirds at a gulf coast stopover site: combining stable isotope and GIS tools. The Condor. 109:256-267.

           In this study, the authors integrate two tools: measurements of stable-hydrogen isotopes (δD), to investigate the region where origin three species of birds were bred, and GIS technology to quantify and depict the origin of the migrating birds. They measured levels of δD in feathers from birds captured in a bird migration stopover located in Alabama, along the Gulf coast. Using an elevation-corrected hydrogen isotope base map for birds of North America, the authors generated a raster image. Then, using a GIS they narrow the areas of species origin by selecting the potential breeding range, by setting a 50% and 75 % data tolerant limits, they depict the probable areas of origin. By integrating relatively abundance data from the BBS, Hobson et al., could even narrow the area of origin of Wood thrush and gray catbird. Thus, even though the delineation of areas of origin can be improved by using additional stable isotope marks, results from the combination of GIS and δD can be substantially useful in bird conservation and migration research.