We have studied the effect of habitat and presence of conspecifics on echolocation characteristics of the emballonurid bat Balantiopteryx plicata. Calls during the search phase only showed differences between habitats in bandwidth, as has been found for other open-space bats. Characteristics of calls during the approach phase did change when bats entered open areas. Calls in the terminal phase showed no differences in the characters examined between habitats. Bats flying in groups shifted their peak frequency significantly, which maximized differences between individuals. These results are interpreted as an active mechanism of jamming avoidance. Bats flying in groups also tended to increase the mean of peak frequencies.