Bats of the genus Carollia feed mainly on plants of the genus Piper, dispersing their seeds in all localities where they occur together. Interactions among these bats, their food plants, and the climate were studied in an Atlantic Forest area in Southeastern Brazil. Path analysis was used to estimate the strength of direct and indirect effects through which variables determine the timing of bat reproduction. Temperature had a small direct influence, but a strong indirect one. Rainfall affected bat reproduction through indirect ways. Although the consumption of Piper fruits by bats did not have a significant influence, the timing of production of Piper fruits was a strong variable directly affecting bat reproduction. We therefore suggest that Piper plants and climate may play a keyrole in the timing of reproduction in C. perspicillata bats.