Dialects

Geographic variation in the structure and complexity of vocalizations has been widely reported for birds (Baker & Cunningham 1985, Kroodsma 2004) and, to a lesser extend, for pinnipeds (Sanvito & Galimberti 2000, Terhune et al. 2008), cetaceans (Weilgart & Whitehead 1997, Deeke et al. 2000, Noad et al. 2000), primates (de la Torre & Snowdon 2009) and bats (Russo & Jones 1999, Davidson & Wilkinson 2002). Geographic variation of vocalizations is often caused by vocal learning but this relation is not mandatory (Janik & Slater 1997, Boughman & Moss 2003). In bats, there has been no evidence for geographic variation of vocalizations through vocal learning so far.

Dialects in territorial songs

Pups of the greater sac-winged bat Saccopteryx bilineata learn an adult vocalization type, the territorial song, through the imitation of tutors (Knörnschild et al. 2010). Thus, this vocalization type could be influenced by cultural transmission, leading to distinct regional dialects.We are currently correlating the acoustic distance between territorial songs of different populations in Central America with the genetic and geographic distance to determine whether acoustic differences between populations are caused by genetic and/or geographic isolation or by vocal learning processes.

Territorial song of a male Saccopteryx bilineata (© Knörnschild).

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