Shrnutí

Popis

Master thesis on the population abundance and genetic structure of black bears in coastal North Carolina and Virginia using noninvasive genetic technigues on Pocosin Lakes, Alligator River and Great Dismal Swamps National Wildlife Refuges. The United States Fish and Wildlife Service USFWS expressed the need to develop appropriate management strategies for apparently highdensity, growing black bear populations in the RoanokeNeuseTarCape Fear ecosystem in coastal North Carolina and Virginia. In order to provide the scientific information necessary to develop these strategies, I investigated population densities and genetic structure of black bears at 3 national wildlife refuges Great Dismal Swamp GDSNWR, Pocosin Lakes PLNWR, and Alligator River ARNWR. Density estimates were derived from DNA samples collected noninvasively at each of the 3 refuges for 2 consecutive summers. Hair samples were analyzed for individual identification using 67 microsatellite markers. Estimated densities were some of the highest reported in the literature and ranged from 0.560.63 bearskm2 at GDSNWR to 0.651.12 bearskm2 at ARNWR to 1.231.66 bearskm2 at PLNWR. Sex ratios were malebiased in all areas of all refuges. Genetic variability and structure of bears at these refuges was assessed using 16 microsatellite markers for 40 bears from each refuge. Genetic variability of the 3 refuge populations was substantially high compared to other bear populations in North America, with observed heterozygosities ranging from 0.6729 at GDSNWR to 0.7219 at ARNWR. FST and DS values were relatively low 0.02570.0895 and 0.09710.3640, respectively, indicating movement of bears and gene flow across the landscape is adequate to prevent high levels of genetic differentiation and structure among the refuge bears. Genetic statistics at GDSNWR indicate that this population is isolated to some degree by geography i.e., the Albemarle Sound and encroaching urban development i.e., the towns of Suffolk and Chesapeake. ARNWR has the potential to become isolated in the future if movement corridors to the south of the refuge are not maintained.Harvest of bears is likely warranted at PLNWR and ARNWR, though extreme caution must be taken the first few seasons as hunter success will be extremely high. Further research is needed to determine population growth rates, reproductive parameters, and survival rates at all 3 refuges, particularly if a hunting season will be established and maintained in these areas. Methods for regularly monitoring bear populations at these refuges also should be incorporated into biological programs, as bears comprise a significant component of the ecosystem at these refuges and cannot be ignored when outlining management goals.