Estimating Population Size of Maryland’s Black Bears
using Hair Snaring and DNA Analysis

Abstract:

Black bear (Ursus americanus) populations have expanded in Maryland since the late 1970s.  Previous attempts to estimate bear numbers have been hampered by access to private land and manpower shortages.  The development of hair snaring techniques, coupled with genetic fingerprinting, provides a more efficient technique than traditional mark-recapture methods to estimate black bear numbers in western Maryland.  In May-June 2000, we established 108 grids throughout occupied bear range in Garrett and western Allegany counties in western Maryland.  We established hair traps in each grid for 4 week-long sampling periods.  Hair samples that were snagged on barbed wire were collected after each sampling period and kept for DNA analysis.  We subjected 330 hair samples to DNA analysis, and identified 92 individual bears.  We identified 45 males and 43 females, and the gender of an additional 4 bears could not be determined.  We used Program CAPTURE to estimate the bear population in western Maryland, and a total of 227 bears (95% C.I. 166-337) were estimated to occupy the 2,152 km² area, 10.5 bears/100km² (95% C.I. 7.7-15.7).  We found this technique to be more practical for estimating bear numbers in western Maryland than the traditional mark-recapture technique of running trap lines.  Costs were substantially less per bear marked in 2000 than previous attempts.

Estimating Maryland's Black Bear Population. Bittner et al.
PDF File (Requires Adobe Acrobat Reader)

If you would prefer to have this document sent by e-mail as a Word File,
please send your request to: customerservice@dnr.state.md.us