Emily Puckett, Alexander Kopatz

American black bears (Ursus americanus) have faced numerous threats since colonization into North America (ca. 1500), including habitat loss, predator persecution, urbanization, and climate change. These threats have caused habitat fragmentation and population declines. Consequently, many populations are vulnerable to inbreeding and genetic erosion, potentially limiting their adaptive potential to ongoing environmental changes. In 2022, the United Nations’ Convention on Biological Diversity adopted the Kunming-Montreal Global Biodiversity Framework (GBF), emphasizing maintenance of genetic diversity across species to preserve their adaptive potential. To standardize monitoring across taxonomic groups, the GBF established three indicators for genetic biodiversity. Here, we report these indicators for American black and polar (U. maritimus) bears: 1) the proportion of populations maintained since 1500, 2) the proportion of extant populations that have an effective population size (Ne) greater than 500, and 3) the proportion of those populations under genetic monitoring. Populations were delimited through a combination of occurrence data, dispersal distance, and genetic analysis from microsatellite datasets. Ne with latitude within U. americanus, where populations at lower latitudes (≥ 36° N) exhibit lower Ne values (range: 3–75). Populations at higher latitudes—which often have more contiguous forests—exhibit higher Ne. For U. maritimus, Ne was highest (range: 347–496) in the Hudson Bay and Canadian Archipelago. Of populations examined, approximately 17% and 0% had Ne > 500 for U. americanus and maritimus, respectively, indicative of genetic erosion. Preliminary trends of small census sizes, severe isolation, and low Ne (< 500) are seen in other Ursid species. By investigating GBF indicators for bears, this study identifies populations at greatest risk of extinction through genetic erosion and highlights areas for long-term genetic monitoring and conservation action.