Abstract
North American rosy-finches (genus Leucosticte ) are cunently classified by the American Ornithologists' Union (1998) as three species - the Brown-capped Rosy-Finch, L. australis, with a breeding range largely restricted to the Colorado Rockies, but extending barely into southeast Wyoming and northern New Mexico, the Black Rosy-Finch, L. atrata, breeding from Utah north through western Wyoming (including GTNP) and west to Idaho and Nevada, and the Gray-crowned Rosy-Finch, L. tephrocotis, breeding from the Sierra Nevada through the Cascades and from northern Montana through the Rockies to Alaska. Based on previous results for a surprising genetic break for black bears (Ursus americanus) across Wyoming, I was interested in the degree of genetic differentiation among populations of rosy-finches, particularly between Brown-capped Rosy-Finches in Colorado and Black Rosy-Finches in Wyoming. Because the mating system is largely unknown, and because of reports in the literature of highly male-biased sex ratios (e.g., 6 males per female; French, 1959), I was also interested in using genetic markers to assess patterns of parentage in rosy-finches. Because of its striking plumage (often indicative of strong sexual selection) I was particularly interested in the Black Rosy-Finch. Using polymorphic microsatellites (nuclear DNA) we have now analyzed an initial sample of individuals from the three North American forms, including three sets of nestling Black Rosy Finches and the behavioral father at one of the nests.