Denning Ecology of American Black Bears in Virginia

1
Denning Ecology of American Black Bears in
Virginia ANDREW S. BRIDGES1, and MICHAEL R.
VAUGHAN2
Figure 1. Den type selection based on 440
observations collected December-April, 1995-2002.

1Department of Fisheries and Wildlife, Virginia
Polytechnic Institute and State University, 149
Cheatham Hall, Blacksburg, VA 24060,
USA. 2Department of Fisheries and Wildlife,
Virginia Cooperative Fish and Wildlife Research
Unit, 148 Cheatham Hall, Blacksburg, VA 24060,
USA.
Abstract American black bears (Ursus
americanus) exhibit decreased activity levels and
may enter a hibernation-like torpor during the
winter. During this time, they may select,
enter, and temporarily reside in den structures.
We collected data on 440 den sites on 2 study
areas in the Alleghany Mountains of Virginia from
1995-2002. A variety of den types were selected,
with tree and snag dens being the most frequent
(Figure 1.) Lone females and females with
newborn cubs preferred tree dens while adult
males and females with yearlings cubs preferred
to den on the ground. We checked 111 den
structures 180 times to see if they were occupied
in subsequent years. Overall, 5.6 (n10) dens
were reused. We found 6 of 141 (4.3) of tree or
snag dens, 3 of 23 (13.0) of rock cavity dens,
and 1 of 5 (20.0) of brush piles, and none of 11
excavations or ground dens were reused. The same
animal that reused the same den in 5 of 10
(50.0) of all documented reuses. Bears entered
their dens between October and January and exited
them from mid March through early May. In 2003,
we used remote cameras to examine denning
behavior (Wildlife Society Bulletin, 32188-193)
and found bears were substantially more active in
March and April than expected. Our results
indicate that tree dens are an important
component in black bear denning ecology in the
Alleghany Mountains. Additionally, because our
final conclusions differed from those based on 3
and 6 years of data, relatively long-term studies
may be necessary to acquire adequate sample
sizes and follow individuals through different
phases of their lives.