Moonlight structures activity patterns of many nocturnal species. Bright moonlight often limits the activity of nocturnal prey, but dense vegetation weakens this effect. Using 8 years of live‐trapping data, we asked whether reintroduced megaherbivores ( Bison bison ) indirectly altered moonlight avoidance by small mammals in tallgrass prairies. In plots with bison, plants intercepted 20% less light, allowing more moonlight to...