Kangaroos are scared by the sound of their own feet thumping on the ground, according to researchers in Australia.
This discovery is being used to stop kangaroos from eating crops and drinking water meant for farm animals.
There could be as many as 60m kangaroos in Australia and farmers are keen to stop them devouring supplies.
A recording of a kangaroo thumping its foot, the noise they make when they sense danger, seems to have frightened off many kangaroos.
A traditional way of scaring kangaroos has been to use loud speakers to send out high-pitched squeals.
But researchers say kangaroos can become used to these sounds and take little notice of them.
It is hoped this foot-thumping technology could also be used to guide kangaroos away from busy roads to stop them getting hit by cars and trucks.