Echolocation Precursor Calls of Kerivoula furva Pups May Contain Individual Signatures

Pups of bats emit isolation calls and the precursor of echolocation calls (echolocation precursors) during postnatal growth. Isolation calls are used by neonates to solicit maternal care. In some species, isolation calls contain individual signatures that allow the mother bat to distinguish its own offspring from others. Little is known, however, about whether echolocation precursors also contain individual signatures. This study examined the postnatal growth and ontogeny of vocalizations in free-ranging Kerivoula furva, a social bat that uses the furled leaves of banana plants as day roosts. We tested the hypothesis that echolocation precursors of K. furva pups contain individual signatures. We found pups of K. furva emitted both isolation calls and echolocation precursors on the day of birth, indicating the two types of call develop independently. The call parameters of the echolocation precursors changed as pups aged, with the frequency increasing and pulse duration decreasing. The echolocation precursors resemble adult echolocation calls when pups reach approximately 25–30 days old. The results also showed the parameters of echolocation precursors differ significantly among pups that roosted together. We suggest echolocation precursors might function as communication signals for mother-offspring recognition.