Acoustic Communication by Animals

Photo by "mali mish" on Flickr

Photo by Joe Shlabotnik on Flickr

I’ve just returned from a conference on “Acoustic Communication by Animals” at Cornell University. This was sort of a “vacation conference” for me as it was attended by a broad cross section of bio-acousticians outside of the usual marine mammals and fish folks found in the ocean noise-oriented meetings. With specialists in bats, birds, insects, frogs, hearing physiology and neurology etc., the meeting allowed me to indulge in my generalist predilections; in this case with a presentation on “chorusing.

Chorusing is usually defined as “acoustic signaling produced collectively by a group of individuals whose activity is clustered in both space and time… which may be temporally structured in alternating or synchronous formats.” The point of my paper was to expand the definition to:

Individual response to signals generated by another or other individuals within a group context that unifies the group in an aggregate behavior.

The reasoning behind this expanded definition is to move the discussion  outside of the usual “individual animal’s breeding and territory needs” and into a context of animals behaving as “acoustic communities.” I’m advancing this because I feel that animals subject to the impacts of human enterprise are much more than “bags of protein with behaviors” or “input devices” – definitions by which they often seem to be evaluated. This broader definition also helps explain the stunning flock behavior of starlings and equally stunning schooling behavior of sharks and forage fish.

In the presentation I qualify both of these behaviors as acoustically stimulated “spatial chorusing.” If you take an individual fish or bird out of these “choruses” and put them in a lab they cease being complete animals. While they are easier to evaluate as specimens, much of what community animals do – and how they are potentially compromised in their habitat by our actions – is lost in translation.

I believe that the aggregate behavior of an acoustic community can tell us much more about species vulnerabilities as well as resilience to human generated noise. Without this consideration we may be missing some opportunities.