Niche partitioning is a strategy that favors the coexistence of sympatric species and prevents resource competition. Resource partitioning not only occurs along a temporal and spatial axis, but also within the niche breadth. The lesser long-nosed (Leptonycteris yerbabuenae) and the Pallas's long-tongued (Glossophaga soricina) bats are sympatric throughout much of their distribution range. Both species can be found in the Mexican tropical dry forest and co-occur during the winter in the pacific coast of Michoacán. These bats have similar requirements but differ in morphological characteristics associated with their particular methods for obtaining food. We evaluate whether these species exhibit niche partitioning in diet and activity patterns during their period of coexistence. Bats were sampled each month from April 2016 to March 2017, and mist-nets were set up at ground level from 19:00 to 03:00 h in Lazaro Cardenas, Michoacán. Diet was determined by taking pollen samples from bat fur and feces, and patterns of daily activity were analyzed. We found greater abundance of bats during November to January, which corresponds to the dry season. This abundance may be associated with a greater availability of floral resources in the study area. Bats fed on nectar from plants of the families Bombacaeae, Fabaceae, Convolvulaceae, Apocynaceae, Cactaceae and Rosaseae. We found no evidence that the diet of the species changes in relation to the presence of potential competitors. However, we found niche partitioning in daily activity patterns of G. soricina related to a high density of L. yerbabuenae.