Title page for ETD etd-08292008-063425


Type of Document Master's Thesis
Author Godfrey, Cale L.
URN etd-08292008-063425
Title Reproductive biology and denning ecology of Virginia's exploited black bear population
Degree Master of Science
Department Wildlife Sciences
Advisory Committee
Advisor Name Title
Martin, Dennis D. Committee Chair
Vaughan, Michael R. Committee Chair
Kirkpatrick, Roy L. Committee Member
Stauffer, Dean F. Committee Member
Keywords
  • denning ecology
  • Ursus americanus
  • black bear
  • reproductive biology
  • Virginia
Date of Defense 1996-12-05
Availability restricted
Abstract

During 1994-1996, reproductive biology and denning ecology of black bears (Ursus americanus) were investigated in the George Washington and Jefferson National Forests, Virginia. The average age of captured bears was 4.88 years (SE=0.43, n=64) and 2.72 years (SE=0.19, n=127) for females and males, respectively. Timing of estrus ranged from 21 June to 7 August with most (58.8%, n=10) estrus females captured between 15 July and 31 July. Ages of primiparity were 3 or 4 years and averaged 3.14 years (SE=0.14, n=7). Average litter size was 2.0 cubs per litter (n=26). During 1995 and 1996, respectively, 81.8% and 83.3% of potentially pregnant females reproduced. Date of parturition averaged 22 January in 1995 and 1996, but ranged from 1 January to 22 February in 1995 and 11 January to 14 February in 1996. Pregnant females did not enter dens earlier (T=0.74, P=0.4598) than other bears, and did not emerge later (T=-1.69, P=0.0925) than other bears. cavities in trees and snags composed 82.4% (n=56) of all dens. Red oak (Quercus rubra) and chestnut oak (Quercus prinus) were the most commonly (n=49) used den tree species. Tree dens were on sites with steeper slopes (t=3.41, P=0.0013), lower medium tree density (t=-2.22, P=0.0313), higher large tree density (t=2.24, P=0.0296), and lower stem density (t=-3.43, P=0.0013) than random sites. Ground dens were on steeper slopes t=3. 22, P=O. 0122) than random sites. Den reuse occurred at 2 of 17 (11.8%) dens, and 84.6% (11 of 13) of bears, monitored both winters, used the same den type during both winters. Virginia's black bear harvest during 1982-1994 was used to reconstruct Virginia's bear population. During 1982-1991, Virginia I s reconstructed male black bear population ranged from 880 bears to 1,241 bears. Numbers of males increased during 1982-1986, declined during 1987-1989, and increased during 1990-1991. Virginia's reconstructed female black bear population ranged from 943 bears to 1064 bears and increased most years.

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