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Documented known and probable grizzly bear mortalities in the Greater Yellowstone Ecosystem, 2015-2025 (ver. 5.0 June 2026)

Published by U.S. Geological Survey | Department of the Interior | Catalog Last Checked: August 01, 2026 at 05:57 AM | Dataset Last Updated: June 22, 2026 at 12:00 AM
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.

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