Counting cats is hard, but we know the numbers aren’t good

a leopard in a tree

Leopards are one of many big cat species that have proven difficult to track — but that are known to be in trouble nonetheless.

Peet van Schalkwyk/Flickr (CC-BY 2.0)

In April, headlines proclaimed that the tiger population was finally showing signs of recovery; a new report from the World Wildlife Fund had found that numbers of the cats had grown from 3,200 in 2010 to 3,890 in the organization’s recent census. After a century of tiger numbers dropping due to poaching and habitat loss, this looked like good news.

Not so fast, said tiger biologists who were not convinced by the results of the census. “We do not find this report and its implications scientifically convincing,” four noted conservation biologists said in a statement. Tigers now occupy only 7 percent of their historical range, they noted, and a recent report found that the cats had lost 40 percent of their habitat in the last decade.

The biologists also questioned the count itself. The WWF report noted that improved census techniques in places like Bhutan might account for some of the increase. And in India, surveys had been expanded to include tigers that lived outside reserves. That makes it nigh impossible to tell whether the increase detected was due to multiplying tigers or better counting methods. And it calls into question the report’s claim that the goal of doubling the tiger population by 2022 is within reach. That “is not a realistic proposition,” the biologists said.

Counting animals is inherently difficult — they rarely line up in a neat row out in the open for scientists to count one-by-one. And while one might think that big, furry, brightly colored cats might be easier to count than other creatures, that’s not necessarily so. And these big cats bring the added problem that they can kill those counting them.

Two new studies of big cats show just how difficult it can be to get anywhere close to an accurate assessment of their status. In the first, published May 2 in PLOS ONE, Femke Broekhuis and Arjun Gopalaswamy of the University of Oxford counted cheetahs in Kenya’s Maasai Mara National Reserve. They searched for cheetahs in the reserve and surrounding areas, photographing the cats so that they could identify each based on its coat pattern. They then applied a statistical technique to estimate how many cheetahs were in the area.

The study revealed that there were only 30 cheetahs in the Maasai Mara, far fewer than what had been thought. Previous studies may have overestimated the numbers of animals by counting cheetahs just passing through an area as permanent residents. By using a method that kept track of individual animals, the researchers were able to eliminate that problem and get a closer estimate of the animals’ true numbers.

Even evaluating where big cats are found can be difficult, as the second study, published May 4 in PeerJ, shows. It looks at leopards and doesn’t try to get numbers of animals but simply the range in which they live and how that has changed over time.

The team, led by Andrew Jacobson of the Zoological Society of London and University College London, compiled 6,000 records of the animals at 2,500 locations taken from over 1,300 sources. The researchers consulted more than 75 experts and reviewed 330 journal articles published since 2000. With that information, they were able to determine that leopards have lost 63 to 75 percent of their historic range, though some subspecies have had their range shrunk by as much as 98 percent. And protected areas aren’t always a great help as they often don’t overlap with where leopards live, the researchers note. The cats also have to deal with hunting and loss of prey.

Whatever their total numbers are, leopards are in serious trouble, like tigers, cheetahs and other big cat species. While there are success stories and places in which the animals are doing well, the larger story is one of animals in need of help. And that’s a story that shouldn’t be forgotten.

Sarah Zielinski is the Editor, Print at Science News Explores. She has a B.A. in biology from Cornell University and an M.A. in journalism from New York University. She writes about ecology, plants and animals.

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