Human activity, rather than larger predators, is forcing cheetahs to expend more energy in search for prey and may be the major cause of their decline, a new study suggests.
Wild cheetahs are down to under 10,000 from 100,000 a century ago with conventional wisdom blaming bigger predators for monopolising available food as their habitat becomes restricted, researchers said.
The traditional thinking has been that cheetahs no longer have sufficient access to prey to fuel their enormous energy output when engaging in super-fast chases.
In the first study of its kind, academics from Queen's University Belfast, other universities and conservation institutions have made the surprising discovery that, in the main, cheetahs do not use significantly more energy than other, similar-sized mammals.
The scientists also discovered that, in searching for prey, cheetahs incur more energy loss than in outbursts of running which, although spectacular, are infrequent.
So, where their prey have been reduced or re-distributed through human impacts, their ability to balance energy budgets has been severely curtailed.
"We studied 19 free-roaming cheetahs each for two weeks across two sites in southern Africa, one in the Kalahari desert and the other in a wetter area," lead researcher Dr Michael Scantlebury from Queen's School of Biological Sciences said.
"We injected heavy water into the animals before tracking them continuously and collecting their faeces. From these samples, we could determine how much of this heavy water they were losing each day and calculate their energy expenditures.
"What we found was that the cats' energy expenditure was not significantly different from other mammals of similar size - cheetahs may be Ferraris but most of the time they are driving slowly. What our study showed was that their major energy costs seem to be incurred by travelling, rather than securing prey," said Scantlebury.
"They can even withstand other species, such as lions and hyenas, stealing their prey. The reality may be that human activities - for example erecting fences that inhibit free travel or over-hunting cheetah prey - are forcing cheetahs to travel ever-increasing distances and that this may be compromising their energy more than any other single factor.
"Our study, which is the result of ten years' of research, seriously questions previously held assumptions about the factors affecting population viability in large predators threatened by extinction," said Scantlebury.
"Too often we blame lions and hyenas for decimating cheetah populations when in fact, it is likely to be us humans that drive their declines. Imagine how hard it must be for a small cub to follow its mother further and further through the desert to look for food, while she herself is fighting for survival," co-author Dr John Wilson of North Carolina State University said.
The study was published in the international journal Science.
