Mirjam Knoernschild

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Saccopteryx bilineata

This species has a complex vocal repertoire consisting of 10 distinct vocalization types that are often multisyllabic.



            Sb_echolocation.wav                    Sb_barks.wav                      Sb_chatter.wav                                     Sb_screech.wav

Echolocation pulse:
They are mainly used for orientation. Wile foraging, the fundamental frequency of pulses regularly alternates but this change does not occur within the day-roost. Lactating mothers also produce echolocation pulses in response to isolation calls of their respective pup.

Bark:
Barks resemble echolocation pulses but have most sound energy in the first harmonic. They are sometimes uttered during aggressive interactions.

Chatter:
Chatter trains are often uttered when all bats are hanging quietly in the day-roost and are normally not accompanied or followed by specific behaviors. They are also sometimes found in male courtship song.




           Sb_territorial song.wav

Territorial song:
Territorial songs are uttered by territorial males at dusk and dawn (but also during the day when disturbed) in order to announce their territory ownership. They are also produced during aggressive male-male interactions (in this case, they are often followed by highly stereotypic trills in rapid succession). They begin with variable syllables that gradually merge into stereotypic end syllables (composite syllables with a noisy and a tonal part). Territorial songs are individually distinct. In contrast to isolation calls, territorial songs are not innate and need to be learned de novo through imitation during ontogeny. Even though only adult males produce territorial songs, pups of both sexes practice this vocalization type. The peak frequency of territorial song end syllables is negatively correlated to both reproductive success (successful males call with lower peak frequencies than less successful ones) and the strength of the counter-song response (a low peak frequency triggers a stronger response in playbacks than a high peak frequency).




         Sb_whistle.wav                                  Sb_courtship song.wav

Whistle:
Whistles are uttered by courting males during stereotypic hover flights. The female either answers with echolocation pulses or screeches.

Courtship song:
Courtship songs are uttered by courting males while being perched in the day-roost. They are always directed at one female at a time and often alternate with whistles and attendant hover flights. Courtship songs can last up to an hour and consist of highly variable elements. Variable trills are the most common element in courtship songs. Males have individually distinct trill repertoires. Chatter trains and screeches are also sometimes found in courtship songs. When courting a female for the first time, young usurping males interspace courtship song elements with isolation call end syllables, presumably to announce their identity to the female and appease her.




            Sb_isolation call.wav                                                                                        Sb_directive calls.wav

Isolation call:
Isolation calls are mainly uttered by pups during reunions with their mothers. However, they are also produced by young peripheral males in order to appease territorial males or by young usurping males when courting a female for the first time. Similarly to territorial songs, isolation calls begin with variable syllables that gradually merge into stereotypic end syllables (0.45-0.75s in sonogram). The tonal part of these end syllables is individually distinct. In playbacks, mothers readily discriminate between own and alien pups based on isolation calls alone. Babbling behavior normally develops within isolation calls. Despite the fact that isolation calls are modified based on social influences, the basic structure seems to be innate since pups are able to produce shaky but recognizable isolation calls within hours after birth.

Directive call:
Directive calls are uttered by lactating mothers during reunions with their respective pup, but only when pups are very young. When pups are older, mothers normally use echolocation pulses to answer their pup's calls.




       Sb_babbling_1.wav                                                                          Sb_babbling_2.wav

Babbling:
Pups of both sexes engage in babbling behavior. They combine rendition of all known vocalization types into long bouts. These bouts are either uttered without any obvious behavioral context (when pups are perched by themselves in the roost) or during solicitation attempts (when pups try to persuade their mothers to let them nurse). Babbling normally begins to develop at 3 weeks of age (normally with only a few odd elements embedded in isolation calls) and gets more pronounced during ontogeny (even later, isolation call end syllables are still found in babbling bouts, but other elements prevail). Babbling might be important in order to acquire the complex vocal repertoire needed as adults.

Behr O, von Helversen O. 2004. Behav Ecol Sociobiol 56: 106-115 / Behr O, von Helversen O, Heckel G, Nagy M, Voigt CC, Mayer F. 2006. Behav Ecol 17: 810-817 / Bradbury JW, Emmons L. 1974. Z Tierpsych 36: 137-183 / Bradbury JW, Vehrencamp SL. 1977. Behav Ecol Sociobiol 2: 1-17 / Davidson MS, Wilkinson GS. 2002. J Mammal 83: 526-535 / Davidson MS, Wilkinson GS. 2004. Anim Behav 67: 883-891 / Jung K, Kalko EKV, von Helversen O. 2007. J Zool 272: 125-137 / Knörnschild M, Behr O, von Helversen O. 2006. Naturwissenschaften 93: 451-454 / Knörnschild M, von Helversen O, Mayer F. 2008. Anim Behav 76:1001-1009 / Knörnschild M, Nagy M, Metz M, Mayer F, von Helversen O. 2009. Biol Lett 5(6)  / Voigt CC, Behr O, Caspers B, von Helversen O, Knörnschild M, Mayer F, Nagy M. 2008. J Mammal 89: 1401-1410

The wav files for download are shifted down in frequency and have a reduced sampling rate (100 kHz).