The world is a perilous place for the endangered manatee. While the mammals are at risk from natural threats, human activity also poses a great danger to manatee numbers. Debborah Colbert, from the Association of Zoos and Aquariums, explains that many manatees die and are seriously injured in collisions with boats every year. However, little is known about how manatees perceive their environment. Whether they can localize sounds, and specifically whether they can tell which direction a boat is approaching from, are crucial factors in the development of manatee protection programmes. Colbert and her colleagues from the Universities of Florida and South Florida and the New College of Florida decided to test whether the mammals can pinpoint sound sources. They publish their results on 12 June 2009 in the Journal of Experimental Biology at http://jeb.biologists.org.
Working at the Mote Marine Laboratory and Aquarium in Florida, Colbert was able to work with two male manatees, Hugh and Buffett, when she initiated a research programme to find out more about these enigmatic creatures. Both young males had been trained previously to participate in a series of sensory studies, so Colbert, Joseph Gaspard 3rd, Gordon Bauer and Roger Reep trained the animals to swim to a specific stationing platform in their enclosure where they could listen to sounds played from one of four speakers arranged around their heads.
Knowing that the manatees' hearing was most sensitive to sounds ranging from 10 to 20kHz, while the animals' calls range from 2.5 to 6kHz, Colbert and David Mann designed three sounds ranging from 0.2 to 20kHz, 6 to 20kHz and 0.2 to 2kHz to play to the animals. The team also selected two single frequency (tonal) sounds at 4kHz and 16kHz to test how the manatees responded to less complex sounds. Having trained the manatees to swim to the speaker that they thought the sound came from, the team then pla
|Contact: Kathryn Knight|
The Company of Biologists