Hokkaido brown bear-related human injuries: a public-record cohort with nested clinical characterization

Human injuries caused by Hokkaido brown bears have been described in fragmented public and clinical records. We conducted a retrospective descriptive public record cohort study of Hokkaido brown bear attack episodes from 2019 to 2024, supplemented by linked clinical records for selected episodes. The primary aim was to characterize publicly recorded episodes and victims; exploratory analyses compared fatal episode proportions by attack time grouping and broad activity context, and the linked clinical subset was used for descriptive clinical characterization only. Among 28 episodes involving 36 victims, seven (25.0%) were fatal. At the victim level, 17 injuries were minor, 12 severe, and seven fatal. Fatal episodes occurred in seven of 16 solo-coded episodes (43.8%) and none of 11 group-coded episodes (0.0%; two-sided Fisher exact P = 0.0216), an exploratory, noncausal association. Seven victims from five episodes were linked to clinical records. Their injuries included complex craniofacial and soft tissue trauma, ocular injury, open fractures, major vascular injury, and thoracic trauma; all received plastic and reconstructive surgical care, with additional specialty involvement in selected cases. This study describes recent Hokkaido brown bear attack episodes using a public record cohort with transparent source documentation and linked clinical details for selected cases. Because of the small number of episodes, potential public record ascertainment bias, and the nonrepresentative clinical subset, the findings should be interpreted descriptively and as hypothesis generating.