Accurate sex identification is necessary for a broad spectrum of bird studies, including brood sex ratios, sex differences in migration timing, sex-biased behavior, and sex differences in physiological responses. However, for sexually monomorphic species, neither structural measurements nor external plumage characteristics can be used to assign sex reliably (Morrison and Maltbie 1999, D’Aloia 2002). In those cases, DNA sexing has proven to be a reliable, efficient method for sexing birds (Kahn et al. 1998, Fridolfsson and Ellegren 1999, Oddie and Griffiths 2002) including some raptor species (Norris-Caneda and Elliott 1998, Balbontin et al. 2001, Shepard et al. 2004).