Documented known and probable grizzly bear mortalities in the Greater Yellowstone Ecosystem, 2015-2024 (ver. 4.0 May 2025)

The Interagency Grizzly Bear Study Team (IGBST) evaluates mortalities for population segments within the DMA by deriving estimates of total mortality for independent-age (2 years or older) females and independent-age males, including estimates of unknown/unreported mortalities based on Cherry et al. (2002). We then determine the total annual mortality rate for these segments as a percent of their respective population estimates. For dependent-age bears (less than 2 years old), we determine the percent of human-caused mortality relative to size of the population segment but do not include estimates of unknown/unreported mortality. Mortality data in this data release represent the individual records documented by the Interagency Grizzly Bear Study Team on an annual basis. Included are all mortality records since 2015. Earlier mortality records can be obtained from annual reports from the Interagency Grizzly Bear Study Team.

Literature cited:
Cherry, S., M. A. Haroldson, J. Robison-Cox, and C. C. Schwartz. 2002. Estimating total human-caused mortality from reported mortality using data from radio-instrumented grizzly bears. Ursus 13:175–184.

First release: 2022

Revised: April 2023 (ver. 2.0)

Revised: June 2024 (ver. 3.0)

Revised: May 2025 (ver. 4.0)