Monster Seminar JAM - Demography and Genetic Structure of a Recovering Grizzly Bear Population
Katherine Kendall, Northern Rocky Mountain Science Center, USGS
The threatened grizzly bear (Ursus arctos) population in northwestern Montana has been managed for recovery since 1975, yet no rigorous data were available to monitor program success. We used data from a large noninvasive genetic sampling effort conducted in 2004 and 33 years of physical captures to assess the abundance, distribution, and genetic structure of this population. We combined data from 3 sampling methods (hair trap, bear rub, and physical capture) to construct individual bear encounter histories for use in HugginsPledger closed markrecapture models. Our population estimate, = 765 (CV = 3.8%) was more than double the existing estimate derived from sightings of females with young. Based on our results, the estimated known, humancaused mortality rate in 2004 was a 4.6% (95% CI: 4.24.9%), slightly above the 4% considered sustainable; however, the high proportion of female mortalities raises concern. Using location data from genetic sampling, telemetry, and confirmed sightings, we found that grizzly bears occupied 33,480 km2 in the NCDE during 19942007, including 10,340 km2 outside the recovery zone. We used factorial correspondence analysis to identify potential barriers to gene flow within this population. Our results suggested that genetic interchange recently increased in areas with low gene flow; however, we also detected evidence of incipient fragmentation across the major transportation corridor in this ecosystem. Our results suggest that the NCDE population is faring better than previously thought, and highlight the need for a more rigorous monitoring program than the Grizzly Bear Recovery Plan specifies.
Date and Time:
April 15, 2010,
11:00 am - 12:00 pm