Dining from the coast to the summit: Salmon and pine nuts determine the summer body condition of female brown bears on the Shiretoko Peninsula

Female brown bears on the Shiretoko Peninsula experience seasonal fluctuations in body condition, primarily driven by their access to high-lipid pine nuts and high-protein salmon. A six-year study (2012–2018) found that while body condition declined until late August, it began to recover in September when salmon consumption peaked. Years with higher intake of both pine nuts and salmon saw earlier recovery in body condition. Additionally, females with offspring had poorer body condition than solitary ones, especially during low-salmon years. The research used scat analysis (2,079 samples) and photographic measurements (1,226 images from 12 bears) to quantify diet and body condition, revealing the critical role of these unique coastal and subalpine foods in bear survival and reproduction.

Shirane, Y., Jimbo, M., Yamanaka, M., Nakanishi, M., Mori, F., Ishinazaka, T., Sashika, M., Tsubota, T., & Shimozuru, M. (2021). Dining from the coast to the summit: Salmon and pine nuts determine the summer body condition of female brown bears on the Shiretoko Peninsula. Ecology and Evolution, 11(10), 5204–5219. Portico. https://doi.org/10.1002/ece3.7410