Grizzly Bear Population Augmentation In The Cabinet Mountains Of Northwest Montana Wayne Kasworm,* USDA Fish and Wildlife Service, Libby

Abstract

The Cabinet Mountains grizzly bear (Ursus arctos horribilis) population was estimated at 15 or fewer individuals in 1988 and believed to be declining toward extinction. In response to this decline, a test of population augmentation techniques was conducted during 1990- 1994 when four subadult female grizzly bears were transplanted to the area. Two criteria were identified as measures of success: bears must remain in the target area for one year, and bears should ultimately breed with native male grizzly bears and reproduce. Reproductive success of any of the remaining individuals could not be established until 2006 when genetic analysis of hair snag samples collected from 2002-2005 indicated that one of the transplanted bears remained in the Cabinet Mountains and had reproduced. The detected bear was transplanted in 1993 as a 2-year-old and was identified by a hair snag within 5 mi of the original release site. Genetic analysis indicated she had produced at least six offspring, and two of her female offspring had also reproduced. This reproduction indicates that the original test of augmentation was successful with at least one of the transplanted individuals. Success of the grizzly bear augmentation test prompted continuation of this effort. The Northern Continental Divide Ecosystem area of north central Montana has been the source of seven additional bears transplanted to the Cabinet Mountains during 2005-2010. All were female bears except one: a young male was moved in 2010. Two female bears were killed and two female bears left the area. Fates and movements of these bears are discussed.