- Science
- Not Exactly Rocket Science
Cheetahs Prosper: New Study Debunks More Old Myths
The cheetah’s life is reputedly balanced on an energetic cliff. Yes, it’s the fastest land animal, capable of going from 0 to 60 miles per hour in a few seconds. But, according to countless nature documentaries, its high-speed chases leave it exhausted and overheated. If it fails to catch a meal, it’s in bad shape to try again. And even if it’s successful, it is easily and frequently driven away from its own kills by more powerful predators like lions or hyenas. The price of super-speed is a teetering existence, spent scrabbling for food and energy.
Except, very little of that is true.
The cheetah’s true biology is clouded in myth, in speculations that have been passed down through so many wildlife programs that people mistake them for fact. Some of these apocrypha pan out. Their record-breaking top speed was based on a single measurement taken in the 1960s, but a recent study that outfitted wild cheetahs with sophisticated tracking collars confirmed that they really are as fast as claimed. Other factoids have been debunked: they don’t, for example, overheat while hunting.
Now, Mike Scantlebury from Queen’s University Belfast has deflated a few other cheetah myths. By tracking several wild individuals, he showed that cheetahs spend most of their energy walking around in search of prey. The actual high-speed chases are over so fast that they’re mere blips on the animals’ energy accounts. Scantlebury also found that cheetahs only lose about 1 in 10 kills to thieving lions and hyenas, and they can easily compensate for the loss with an extra hour of hunting.
“They’re fairly robust, much more so than we thought they were,” says Scantlebury. “Left to their own devices, they’re pretty good at surviving.”
Over two-week periods, his team followed 14 cheetahs in Botswana’s Kgalagadi Transfrontier Park, and five living freely in South Africa’s Karongwe Game Reserve. They noted whether the animals with lying, walking, sitting, or chasing. They also measured how much energy the cheetahs were burning by injecting them with a form of water that contained slightly heavier versions of the usual hydrogen and oxygen atoms. By looking for the same atoms in the cheetah’s faeces, the team could work out how quickly they passed through the animals’ bodies, and thus how much energy the cheetahs were using.
“We thought that they would have a high energy expenditure just to survive. If you have a supreme engine, just maintaining it would be costly,” says Scantlebury. They were wrong. In fact, the cheetahs were burning as much energy as you’d predict for an animal of their size. They have big hearts, lungs and liver, and their muscles can generate an extreme amount of power when they sprint. But most of the time, their energy costs are low.
Even their famous hunts don’t tip the scales. The team found that the cheetahs spent roughly the same amount of energy on days with chases as on days without them. That’s because each chase, while intense, lasts for an average of 38 seconds, and cheetahs rarely sprint more than once a day; on average, a cheetah sprints for just 45 seconds each day! By contrast, they spend several hours just walking around in search of prey to sprint after, and these treks sap the largest proportion of their energy. Finding something to sprint after is more costly than the actual sprints.
If cheetahs lose their kills to another predator, they can usually find more potential prey nearby. They can try to catch another one within the hour, without having to do a long searching walk. In fact, the team calculated that cheetahs could lose half of their kills to lions or hyenas, and still break even energetically. As it is, they only lose a tenth. “I think they just don’t bother hunting if there’s lots of other predators around,” says Scantlebury.
For comparison, African wild dogs, which have the highest success rates of all the African predators, suffer more greatly if their food is stolen. These animals wear down their prey through long, dogged chases that can last for several hours. Unlike cheetahs, they burn a tremendous amount of energy during their actual hunts. Losing a meal matters greatly to them.
These results have important implications for protecting the 10,000 or fewer cheetahs left in the wild. “Anything that makes them travel further will increase their energy expenditure,” says Scantlebury. A fence or human settlement that forces them to walk long distances in search of prey might turn them into the energetic paupers that we have mistakenly mythologised them as.
Reference: Scantlebury, Mills, Wilson, Wilson, Mills, Durant, Bennett, Bradford, Marks & Speakman. 2014. Flexible energetics of cheetah hunting strategies provide resistance against kleptoparasitism. Science http://dx.doi.org/10.1126/science.1256424
