猎豹，瞬时加速专家

RENEE MONTAGNE, HOST: The cheetah is the fastest animal on land. It has been clocked at 65 miles an hour. It turns out that amazing speed isn't the key to its success as a predator. NPR's Rhitu Chatterjee reports on a new study that suggests when it comes to hunting, it's not the cheetah's agility that counts.

RHITU CHATTERJEE, BYLINE: The closest most of us ever get to a cheetah is National Geographic Channel.

(SOUNDBITE OF NATIONAL GEOGRAPHIC CHANNEL)

UNIDENTIFIED MAN: This is the Cheetah. It's doing what cheetahs do best - running, flat out, after prey.

CHATTERJEE: These documentaries always go on about how fast the cheetah can run. But believe it or not, scientists know very little about how the animal runs in the wild, especially when on the hunt.

ALAN WILSON: You can look at it and say, oh, that's fast. But you can't actually describe what route it follows, or how quickly it's gone, or the details of what forces it's having to exert to do that.

CHATTERJEE: Alan Wilson is at the Royal Veterinary College, in London and an author on the new study. He and his colleagues tracked a group of wild cheetahs in the Okavango Delta in Northern Botswana. Wilson designed a sophisticated radio collar he could place on the animal.

WILSON: It has a GPS that gives you a position and speed five times a second. It has got accelerometers, and gyroscopes and electronic compasses in it.

CHATTERJEE: Together, these instruments collected detailed information about the animals' movements. Like how fast they ran when hunting, how quickly they sped up, or slowed down and how and when they changed directions. Wilson says the animals reached top speeds of 45 to 58 miles per hour. But, he says...

WILSON: On an average hunt they're only achieving half the maximum speed.

CHATTERJEE: In other words, running at top speed didn't seem all that necessary for hunting. What mattered more is how fast a cheetah could accelerate.

WILSON: We saw remarkably high accelerations, four times higher power than we see for Usain Bolt when he ran his world record.

CHATTERJEE: Wilson says the animals were equally capable of slowing down quickly and turning sharp corners.

WILSON: They can accelerate, they can maneuver, they can duck and dive. And that's what they need to do to actually capture their prey.

CHATTERJEE: Wilson's findings appear in the latest issue of the journal Nature. He says data from the collars clearly showed that agility trumps speed, especially in bringing a hunt to a successful end.

WILSON: That sort of end phase, when they're maneuvering, when they're turning sharply, when they're stopping and starting, is where the prey will escape or not escape. So that sort of final maneuvering phase seems to be very important.

CHATTERJEE: Andrew Biewener is a biologist at Harvard University. He studies how animals move.

ANDREW BIEWENER: We all know that cheetahs are very fast.

CHATTERJEE: But, he says, this study is the first to give hard data on exactly how cheetahs move in the wild. And beyond that, he says, the tools used in the study can help protect the cheetah because it's an endangered species. He says the radio collars paint a picture of cheetahs in their natural environment.

BIEWENER: That gives more of a window into what kinds of habitats need to be protected to allow these animals to survive as increasing pressures are put on their natural wildlife areas.

CHATTERJEE: Wilson is already on the task. Now that he's followed individual hunts, he plans to map the Cheetah's range. Rhitu Chatterjee, NPR News.