Calls of longer duration separated by short periods of silence (high duty cycle). May be a specialization associated with collecting more details about fluttering targets in clutter (Fenton, 873)
Habitat: Lowland tropical wet forest to arid thorn forest, at elevations from sea level to ~3000m. Roosts in mine tunnels and caves with a large number of other bat species, prefers high humidity (Gardner, 383).
- These bats use Doppler shift compensation to determine the relative position and velocity of their prey. The phenomenon known as the Doppler Effect is a change in the observed frequency of a wave (in this case sound), occurring when the source (bug) and observer (bat) are in motion relative to each other, with the frequency increasing (pitch sounds higher) when the source and observer approach each other, and decreasing when they move apart. For instance, the siren of an ambulance or police car often sounds higher in pitch as it approaches, and as soon as it passes, the pitch decreases. Echo locating bats also encounter this problem: if their prey is moving away from them at the time they emit a call, the returning echo will be lower than the emitted call. Likewise, if their prey is moving towards them, the returning echo will be higher than the emitted call. Parnell’s mustached bat is one of the few Neotropical bats known to compensate for the Doppler shift – the bat will lower the frequency of its call so that the echo returns at a frequency the bat is most sensitive to (acoustic fovea).