Pteronotus parnellii, the Common mustached bat, is a member of the Neotropical family Mormoopidae. These bats are native to Central and South America, where they commonly roost in caves and large tree hollows. Pteronotus parnellii is the only member of its family (indeed, the only bat in the New World) to use Doppler shift echocation. They have an unusual, highly specialized echolocation system that takes advantage of the Doppler shift to separate emitted pulses (calls) and returning echoes in frequency rather than in time. These bats simultaneously emit long, constant frequency calls and listen to returning echoes, and analyze the resulting auditory data to build a complex, dynamic auditory map of their environment. An anatomical feature associated with use of Doppler shift echolocation is an extremely large cochlea, in which the basal turn is tuned to be especially sensitive to the frequency of returning echoes, which are lower frequency than the calls emitted by the bat.