Kangaroos kept on the hop by biologist

Press, 10 January 1986, Page 22

Kangaroos kept on the hop by biologist

NZPA-AAP New York Australian red kangaroos are probably the most efficient animal in the world, according to a recent Harvard University study. This two-metre tall living pogo stick has a top speed about three times as fast as a marathon runner — more than 60km

— with each hop extending nearly 6 metres. The Australian biologist, Dr Terence Dawson, has spent 15 years trying to learn the secret of the kangaroo’s hop, which he regards as one of the most efficient forms of mobility on land.

Dr Dawson brought four gAustralian red kangaroos to Harvard University to watch and measure them hop on treadmills. He put oxygen masks on the animals and attached monitors to measure temperature and heart rate. After a series of tests, he concluded that only some dogs, which run with long galloping strides, are any-

where near as efficient as kangaroos. When the kangaroo hits the ground, it stretches the elastic tendons and ligaments that run throughout its body, storing energy in much the same way as the spring in a pogo stick.

As the animal launches itself in a hop, the energy is released. Most other animals, including humans, store very little energy as they move, and each time they take a step, almost all energy is lost and their muscles must work to produce new energy. Two of the kangaroos would not co-operate, but Dr Dawson said the others liked the tests.

“One of them got to the stage where when you opened its cage in the morning, it hopped out on to the treadmill and waited for it to be switched on,” he said. Dr Dawson believes kangaroos may have started hopping to overcome low body temperature, caused

by their less developed metabolism compared with other mammals.

“At low speeds, they’re not very agile,” he explained. “But once they get their first half-dozen hops in, they’re off.” He has also studied kangaroo behaviour, using volunteers from an American group called Earthwatch to observe the animals in their natural habitat, using radio transmitters to record their movements.

Dr Dawson was surpised to discover that kangaroos do not hop much at all. “They’re fairly lazy animals,” he said. Like many of their human counterparts Down Under, they love lying around in the sun, sometimes with their legs in the air. “It’s rather odd when you first see a kangaroo lying in a dust bowl with its legs in the air relaxing,” he said. No doubt, the kangaroos had a similar experience when they first saw Australians sun-bathing.