Where Are You?

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Each white dot is where an elephant was standing when it rumbled, recorded using an acoustic array (yellow spots). The array lets us use slight differences in the time of arrival of the same rumble to triangulate to where the elephant was located. The blue area is the forest clearing, the blue line a river, and the red dashed line our trail through the forest from camp.

Acoustic arrays, which allow us to tell where a call originated, are very powerful tools. They are also rather intensive to use because an array typically needs five or more recording units, they must have clocks synchronized to the millisecond level of accuracy, and they need to be spaced close enough together that three or more record the same call.

Below is a short animation that shows how this works.

Acoustic arrays are critical for answering questions like:

         – How many calls does a single elephant make in a given time period? (We need this to estimate the size of an elephant population from calls sampled across a huge landscape.)

         – When calls can be so low that we can’t hear them from an observation tower, an array can tell us who gave a call that was associated with some interesting behavior. (We are doing this at the Dzanga Bai to probe the “elephant dictionary” or to find out who called at night.)

         – We can follow the fine-scale movements of individual elephants as they approach a forest clearing (or as they leave it). (In the figure at the top of this page we followed a young male who was nervous about entering the clearing where a big bull was hogging the drinking hole.)

Explore how we eavesdrop on forest elephants

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