Bat Communication Lab

Kirsten “Kisi” Bohn

Johns Hopkins University


We are interested in the evolution of vocal complexity. Everyone would agree that humans have the greatest vocal complexity known, however, even though a great deal of research has focused on speech production and how language evolved, these topics remain highly controversial. This is in part because only a handful of animals use complex vocal signals. Indeed, birdsong has been our main model for the neurophysiology of speech and the evolution of complex vocalizations. Our goal is to add bats as a comparative model to better understand the production and evolution of vocal complexity, including human speech. 

Why Bats?

Bats are superb subjects for studying vocal complexity- they are extremely social, very vocal and have a highly specialized audio-vocal system for echolocation. This sonar system requires neurocircuitry for using incoming echoes to rapidly modify outgoing vocalizations.  Furthermore - almost nothing is known about social communication compared to other animals. This is because historically it was nearly impossible to record ultrasonic vocalizations in the field or observe behaviors in low light conditions. The recent development of high
speed data acquisition cards, small laptop computers with large storage capabilities, infrared lights and weather resistant ultrasonic microphones has resulted in a plethora of new data and discoveries. Bats are essentially a new unexplored frontier of animal communication and with over 1,100 species the possibilities are immense.

Bat Songs

Video of Bat Song

Brazilian (aka Mexican) free-tailed bats  (Tadarida brasiliensis) are small insectivorous Molossids that are widely distributed from the central United States through central South America. During the mating season, males establish roosting territories which they aggressively defend from males while allowing females to reside. We discovered that during this time males vocalize, in fact, the free-tailed bat is a mammal that sings like a bird! By song we mean “ vocalizations produced by males in in courtship (mate attraction or territorial defense)  composed of multiple types of syllables combined in specific ways, and which have repeatable patterns and rhythm”.

The free-tails are the only mammals other than cetaceans that produce songs that are hierarchically structured (syllables are combined to form phrases and phrases are combined to form songs). Songs also show flexible syntax, that is the number and order of phrases vary from one song to the next. However, song syntax is also non-random, following specific structural rules. See Tadarida page for more information on songs.

Song of another male, click to play (slowed 8x).

What are we working on now?

  1. 1)To what extent are songs innate, learned or modified by social experience? Tadarida, Nyctinomops

  2. 2) Is the neurocircuitry of vocal production more like other mammals or songbirds (and humans)?

  3. 3)How do songs evolve? To what extent do they evolve independently of the echolocation system?