The number of cheetahs in the world has dropped sharply in the past century, and humans may be to blame, according to an international study released Thursday.
The findings contradict previous research that pointed to larger predators as the source of the cheetahs' decline, either by killing the fast cats or stealing their food.
But the latest research in the journal Science found that cheetahs have to travel much farther than they used to in order to find food due to human encroachment, fence building and loss of expansive open habitat.
Cheetah populations have dropped from 100,000 in 1900 to about 10,000 today worldwide, the study said.
"They remain remarkably adapted and resilient," said Michael Scantlebury from Queen's University Belfast's School of Biological Sciences.
"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."
For the study, researchers tracked 19 free-roaming cheetahs -- each for two weeks -- at two different sites in southern Africa.
They injected the animals with an isotope-laden water that would allow researchers to analyze the cheetahs' feces and see how much energy the animals had expended.
"What we found was that the cats' energy expenditure was not significantly different from other mammals of similar size," said Scantlebury.
"Cheetahs may be Ferraris but most of the time they are driving slowly."
Cheetahs expended relatively little energy during a hunt, even when they burst into high speed to chase their prey. What took most of their energy was walking great distances to find food in the first place.
Knowing more about the challenges cheetahs face may help conservationists better plan for how to keep the wild cats alive in the future, researchers said.
"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," said co-author John Wilson of North Carolina State University.
"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."