Functions of distress calls in G. soricina

Hörmann D, Tschapka M, Rose A*, Knörnschild M* (2020) Distress calls of nectarivorous bats (Glossophaga soricina) encode individual and species identity. Bioacoustics. *Joint senior authors.

In many bat species, distress calls of trapped individuals provoke approaching behavior of conspecifics. Approaches are often interpreted as ‚inspection flights‘, that are performed to gain information about the situation or predator (informational hypothesis). However, experimental evidence is scarce. If bats perform approaches to gain information, they should learn to fear objects (i.e. artificial predators) that are presented together with playbacks of conspecifics‘ distress calls.

In his masters project, David started with a first round of descriptive and experimental work on distress calls in G. soricina. David analyzed 1925 distress call syllables from 15 individuals, and defined six different syllable types. He found statistical evidence for an individual signature in distress calls, but not for a sex-specific signature. Further, he conducted playback experiments and revealed that the bats’ response behavior to distress calls of conspecifics is influenced by group size (group-housed bats responded to distress calls, whereas single-housed bats did not).

Distress call sequence of G. soricina. The sound file was slowed down by a factor of 10:
Glossophaga distress calls spectrogram


Mother-pup communication

Engler S, Rose A*, Knörnschild M* (2017) Isolation call ontogeny in bat pups (Glossophaga soricina). Behaviour, 154:267-286. *Joint senior authors.

Glossophaga soricina pups produce isolation calls to solicit maternal care. In her study, Sina found strong statistical evidence for an individual signature encoded in isolation calls and revealed that isolation call parameters considerably change over a short ontogenetic time span.

Glossophaga isolation calls recording
Vocalizations of a G. soricina pup are recorded with an ultrasonic microphone (left). Mother nursing its pup (right).

Isolation calls of a G. soricina pup. The sound file was slowed down by a factor of 10: