We describe and compare field recordings of echolocation calls of the neotropical emballonurid sac-winged bats Balantiopteryx plicata, B. io, and B. infusca. These 3 species have search-phase calls with principal energy in the 2nd harmonic, characterized by a long narrowband component followed by a short broadband component. Variation in call parameters follows only partially the scaling pattern with body size generally found in bats. Based on characteristics of their echolocation calls, we hypothesize that B. io and B. infusca forage in more cluttered habitats than does the congeneric B. plicata, which typically hunts in open areas.