• Black bear denning ecology and habitat selection in interior Alaska

      Smith, Martin E.; Follmann, Erich; Dean, Fred; Hechtel, John; Bowyer, Terry (1994-12)
      To identify conflicts between existing black bear (Ursus americanus) management and human activity on Tanana River Flats, Alaska, we monitored 27 radio-collared black bears from 1988-1991. We compared denning chronology, den characteristics, den-site selection, and habitat selection across sex, age, and female reproductive classes. Mean den entry was 1 October and emergence was 21 April, with females denned earlier and emerging later than males. Marshland and heath meadow habitats were avoided, and willow-alder was selected for den-sites. Eighty-three percent of dens were excavated, 100% contained nests, 18% were previously used, and 29% had flooded. Black bears selected black spruce-tamarack and birch-aspen significantly more, and marshland and heath meadow significantly less than available. Marshland and birch-aspen were used significantly more in spring than autumn. Marshland was used less than available by all bears in all seasons. Special habitat or den-site requirements are not critical for management of Tanana River Flats black bears.
    • Shoreline distribution and landscape genetics of bears in a recently deglaciated fjord: Glacier Bay, Alaska

      Lewis, Tania M.; Hundertmark, Kris; Pyare, Sanjay; Chapin, F. Stuart, III (2012-05)
      To further knowledge of mammalian colonization patterns following deglaciation, I used occupancy modeling to estimate black and brown bear shoreline distribution of Glacier Bay and how these distributions relates to the number years of land exposure and post glacial plant and stream succession. I also conducted microsatellite genetic analysis of brown bear hair and tissue to determine contemporary population structure throughout the park and how it relates to landscape features and surrounding populations. Closed forest cover within 1 km of the study site was a strong positive predictor of black bear occurrence. Brown bears were detected at 100% of sites although their use was highest in recently glaciated and old growth forest areas, and lowest in young forests. The shoreline of Glacier Bay hosts brown bears from three geographically overlapping distinct populations, one of which is likely composed of the original colonizers following glacial retreat that were isolated long enough to undergo genetic drift. The southern portion of Glacier Bay fjord and the Fairweather Mountain range are barriers to dispersal. Evidence of range expansion and recent migration indicate that brown bears are still actively colonizing Glacier Bay.