Animated image showing grizzly bear range expansion in GYE: 1990-2020
Sequential estimates of occupied ranges for grizzly bears in the Greater Yellowstone Ecosystem during 1990–2020. Range extents are based on methods described in Bjornlie et al. (2014). Verified grizzly bear locations from a variety of sources, including VHF and GPS telemetry locations, sightings, mortalities, and human-bear conflicts for consecutive 10-year period were compiled and mapped onto a 3-km by 3-km (about 1.9 by 1.9 mile) grid. Zonal analysis and ordinary kriging was then applied to develop a predicted surface of occupied range. The procedure was applied to subsequent years by moving up the 15-year time period in 1-year increments (i.e., the frame labeled 1990 used location data obtained during 1976‒1990, the frame labeled 1991 used data obtained during 1977‒1991, etc. through 2020). (Animation by D. Bjornlie, Wyoming Game and Fish Department)
Bjornlie, D.D., Thompson, D.J., Haroldson, M.A., Schwartz, C.C., Gunther, K.A. Cain, S.L., Tyers, D.B., Frey, K.L., and Aber, B., 2014, Methods to estimate distribution and range extent of grizzly bears in the Greater Yellowstone Ecosystem: Wildlife Society Bulletin, v: 38, p: 182–187.