baby bats babble too...

BABBLING bouts of barks by baby bats. It's not a tongue-twister; it's the first example of infant vocalisation in non-primate mammals. In human infants, babbling has an important role in language acquisition, developing the vocal tract and associated musculature. Similar behaviour is seen in other primates and some songbirds. Now a team led by Otto von Helversen at the Friedrich-Alexander University of Erlangen-Nuremberg, Germany, has recorded infant babbling in sac-winged bat pups (Saccopteryx bilineata), a species with an unusually large vocal repertoire. The pups, aged 4 to 8 weeks, uttered renditions of all known adult vocalisations, including barks, chatters and screeches (Naturwissenschaften, DOI: 10.1007/s00114-006-0127-9). A lack of social context implies the pups babble for vocal training rather than communication.
From issue 2562 of New Scientist magazine, 29 July 2006, page 18