Evidence item

Using an 18-year dataset across five Tohoku prefectures, we find that it reflects bears responding to a rhythm breakdown of the forest’s food supply. Conflict rises sharply once mast production falls below a threshold. Around 2006, the mast system passed a break point, after which lean years grew more severe and crossed that threshold more often. Conflict is further amplified when the alternative food source, indexed by primary productivity, fails alongside mast, and the 2023/2025 outbreaks provide a natural experiment separating compound from single-source failure.