There are approximately 10,000 cheetahs in the wild today; a mere 10% of what their numbers were a century ago. Though it has long been thought that larger predators have been out-competing them for food and driving down the population, it now appears that human activity could be the main factor. The research was led by Michael Scantlebury of Queen's University Belfast and the paper was published in Science.
It was previously believed that the cheetah population has been in decline because there isn't enough prety to meet their high energy demands. Scantlebury's team performed unique research into how cheetahs are using their energy and were surprised to find that they don't really use more energy than other big cats, and cheetahs put more energy into finding prey than in chasing it down. With human development and urbanization in the cheetah's range, prey populations have been in decline, causing them to travel longer and farther in search of a meal.
"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," Scantlebury said in a press release. "What our study showed was that their major energy costs seem to be incurred by traveling, rather than securing prey. If you can imagine walking up and down sand dunes in high temperatures day in, day out, with no water to drink, you start to get a feel for how challenging these cats' daily lives are, and yet they remain remarkably adapted and resilient."
He explained that even when competing for resources with other large animals, cheetahs are fairly resilient. The cats are able to continue traveling freely, and will find alternate prey. However, with human urbanization and fences that restrict where they can move, the cheetahs need to travel great distances around the obstacles to find the food that is becoming increasingly scarce due to habitat destruction. This human activity puts too much stress on the cheetahs, and they aren't able to find enough food to meet their needs.
The energy expenditure levels of the cheetahs were measured through their feces. Scantlebury's team injected 19 cats from two different free-roaming sites with heavy water (the molecules use deuterium, a heavier isotope of hydrogen). Over the course of two weeks, the cheetahs were tracked meticulously and their feces was collected. The levels of heavy water were monitored, allowing the researchers to discover how much energy the cats had been expending. Understanding how cheetahs are expending their energy will allow conservationists to better address their needs while rebuilding the species' numbers.
"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," lamented 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."
