David G. Browning decibeldb@aol.com
Peter D. Herstein – netsailor.ph@cox.net
139 Old North Road
Kingston, RI 02881
Popular Version of paper 3pAB1
Presented Tuesday afternoon, June 27, 2017
173rd ASA Meeting, Boston

Are you greeted with a welcoming whinny when you enter the barn? When doing research on horse whinnys (as part of the Equinne Vocalization Project) we realized we were hearing more whinnys when horses were inside the barn than out. This led us to investigate further and we came to realize it was vocalization adaptation. Horses have remarkable eyesight, with almost a 360° field of view, which they primarily rely on to observe and communicate when out in the open. In a barn, confined to a stall, their line of sight is often blocked. Quite remarkably, they learn to compensate by recognizing the sounds that are of interest — like that of the feed-cart or even their owner’s footsteps — which they often salute with a whinny.

We were curious as to how universal vocalization adaptation occurred in the animal world and in searching the literature we found numerous interesting examples. Asian Wild Dogs (Dholes), for example, hunt prey in packs, usually out in the open where they can visually keep track of the prey and their pack mates. When they encounter some sight-limiting vegetation, however, they have developed a short, flat whistle to keep track of each other but not interfere with their listening for the prey.

Jungles, presenting further examples, are uniquely challenging to animals for three reasons: visibility is limited, moving is difficult, and the vocalization has to be heard despite many others’ sounds. African rhinos out on the plain can make do with a simple bellow, as it would be easy to trot over and check them out. In contrast, a Sumartran rhino, always in the jungle, has a complex vocalization. Often compared to that of a whale, the vocalization is complex in order to be heard among the competing calls while providing enough information so to entice another to slog over to check it out (or not).

The military use a term “situational awareness,” that also refers the awareness that is crucial to animals, and this work provides some examples of their acoustic compensations when visibility is limited for some reason.

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