Liver tissue from 1,003 Barred Owls removed across northwestern California between 2019 and 2025 shows that anticoagulant rodenticides remain pervasive in forest food webs, with more than one in three owls exposed. Exposure among young owls declined following California's statewide restrictions, suggesting the regulations are working. At the same time, cholecalciferol, a less regulated rodenticide that also occurs naturally as vitamin D3, was detected in nearly one in five owls and appears to be increasing. Whether these detections reflect rodenticide baits or natural sources cannot yet be fully resolved, but the pattern is consistent with product substitution and warrants further study.