Last year, 73 manatees in Florida were killed by collisions with boats, despite speed restrictions designed to protect them. Edmund Gerstein at Florida Atlantic University in Boca Raton found that the animals cannot hear the low-frequency sound boats make, so he has developed an alarm that emits a high-pitched sound in front of the boat. When he tested it at a wildlife reserve, he found manatees always avoided a boat fitted with the alarm, compared to only 3 per cent of the time for a boat with no alarm.
By bouncing ultrasound off insects, researchers at Pennsylvania State University in…
