Energy Expenditure Of Cheetahs Suggests Humans Are Responsible For Their Decline

Chuck Bednar for redOrbit.com – Your Universe Online
Like housecats, cheetahs spend much of their time relaxing, opting to conserve their energy for the bursts of activity required to take down their prey, according to new research appearing Friday in the journal Science.
However, lead author Dr. David M. Scantlebury of the Queen’s University Belfast School of Biological Sciences and his colleagues report that their analysis of the creatures’ daily energy expenditure revealed that human activity forces them to expend more effort than larger predators, and could be the primary cause of their plummeting population.
In what the researchers are calling the first study of its kind, the authors wrote that cheetahs typically do not expend significantly more energy than other, similar mammals. Furthermore, they found that the cats typically incur more energy loss while searching for food than they do during their spectacular outbursts of running – a discovery which suggests that human-caused reductions or redistribution of their prey has impacted them tremendously.
Dr. Scantlebury explained that he and his fellow researchers looked at 19 free-roaming cheetahs at one of two different sites in southern Africa – one in the Kalahari desert and the other in a wetter region of the continent. Each cheetah was studied for a period of two weeks, and the scientists injected heavy water into the creatures before tracking them and collecting their feces so that they could calculate how much of the liquid they were losing each day.
With that information, they were able to calculate the cheetah’s energy expenditures, and Dr. Scantlebury found the cats were not expending significantly more energy than mammals of similar size. He added that their research showed the major energy costs appeared to be incurred more by traveling than by 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,” the professor said in a statement. “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,” he continued, adding that their study “seriously questions previously held assumptions about the factors affecting population viability in large predators threatened by extinction.”
“Research of this type helps improve our understanding of the challenges facing cheetahs as they strive to survive and helps inform future decisions on conservation strategies for cheetahs and other threatened animals,” said co-researcher Dr. Nikki Marks, also of Queen’s University. Likewise, co-author Dr. John Wilson of North Carolina State University said the study demonstrated that people, not lions or hyenas, were driving the creatures’ decline.

Image Above Credit: Thinkstock.com
A similar study, also published Friday in the journal Science, tracked energy usage for another type of big cat – the mountain lion (or puma) – living in Santa Cruz, California, and found that the creatures used between 10 and 20 percent of their total daily energy taking down prey that can be as much as four times larger than they are.
As Christine Dell’Amore of National Geographic explained, the authors of this study used specially designed radio collars to track the movement and speed of the four wild mountain lions in the Santa Cruz Mountains. While they have calculated how much effort they put into hunting, they have not yet calculated the average kilojoules expended by a mountain lion during an average day.
Lead investigator and University of California, Santa Cruz ecologist Terrie Williams told Dell’Amore that the data collected by her team are especially valuable, as puma attacks are rarely witnessed. Williams added that the work of both research teams has provided information that will prove vital to scientists working to protect big cats.
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