Thursday, May 6, 2010

Bees are Elephant Repellant

A elephant story in today's News-Leader caught my attention.  It reports that elephants are afraid of bees, leaving the area when they find them and warning other elephants nearby.
Lucy King and colleagues report in PLOS that "the sound of disturbed African honeybees Apis meliffera scutellata causes African elephants Loxodonta africana to retreat and produce warning vocalizations that lead other elephants to join the flight."
They used special audio recording devices to record the elephants distinctive "rumble" vocalizations which are below the human hearing range.
"Audio playbacks of bee sounds induced elephants to retreat and elicited more head-shaking and dusting, reactive behaviors that may prevent bee stings, compared to white noise control playbacks. Most importantly, elephants produced distinctive “rumble” vocalizations in response to bee sounds. These rumbles exhibited an upward shift in the second formant location, which implies active vocal tract modulation, compared to rumbles made in response to white noise playbacks. In a second experiment, audio playbacks of these rumbles produced in response to bees elicited increased head shaking, and further and faster retreat behavior in other elephants, compared to control rumble playbacks with lower second formant frequencies."
In addition to advancing our understanding of elephant behavior, these findings may have a practical implication.  A single elephant can destroy an African farmer's gardens and his livelihood in a single night.   They frequently have to guard their plots at night, hoping to scare the elephant away, a dangerous and frequently futile action.  In addition, frustrated farmers frequently kill elephants which is against the law.
A possible application of this research would be to create "bee fences".  Bee hives would be attached to posts connected to each other by wire.  When the elephant hits the wire, the sound of the disturbed bees would alarm the elephant and drive it away.
Unfortunately, this has no apparent application for the raccoons and rabbits in our vegetable garden.

The article appeared in PLOSone.com (Public Library of Science) which is an online peer-reviewed science journal.  The science is high quality and an open access source, meaning you can read the whole article without having to pay to access it.  While usually quite technical, they have a lot of interesting scientific studies.

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