Population Characteristics and the Effects of Hunting on Black Bears in a Portion of Northwestern Montana

• Main Author: Thier, Timothy Joseph
• Other Authors: Thomas Roy
• Format: Others
• Language: en
• Published: The University of Montana 2011
• Subjects: Environmental Studies
• Online Access: http://etd.lib.umt.edu/theses/available/etd-09222011-162242/

Prior information regarding the status of black bears (Ursus americanus) in Hunting District 100 in extreme northwestern Montana was confusing and oftentimes conflicting. To gather information on the population and the effects of hunting, especially during the spring hunting season, 13 black bears were radio-collared and monitored during 1986 and 1987. An additional 15 bears were marked and released. Information was gathered on the age and sex structure of the capture sample, survival and mortality rates of marked bears, reproduction, home range sizes, and hunter technique and effort. A density estimate of 1 black bear/15.4 km2 for the study area was determined. The age structure of captured bears was comprised primarily of adult males, which is generally recognized as indicative of a lightly or unexploited population. However, the mortality of marked bears due to hunting was found excessive. A decrease in the number of bears captured from 1986 to 1987, the large proportion of marked bears killed, and the 1987 spring observation data, all indicate that the study area population was well sampled by trapping. A reproductive rate of 0.70 cubs/female/year was determined, with at least 1 female not producing a successful litter until the age of 7. The mean home range size for adult males (5+ years) using the minimum convex polygon method was 98.7 km2 with a range of 35.5 to 192.6 km2 (n ;: 7). The home range size for adult females was 45.8 km2 with a range of 17.5 to 107.4 km2 (n = 4). Driving open roads was the primary hunting technique used during the spring hunting season. Thirty-nine percent of the bears killed during the spring season were shot within 100 mof an open road, while 66% of the bears were killed after first being observed from an open road.