There is growing evidence that bears are not carnivores

Bears are not cats or dogs, and feeding them as they are is likely to shorten their lives.

A new study in Scientific reports in the diets of giant pandas and sloth bears adds more evidence that bears are omnivores, like humans, and need far less protein than they are typically fed in zoos.

“Bears are not carnivores in the strictest sense, like cats, when they consume high protein diet” said lead author Charles Robbins, a professor of wildlife biology at Washington State University. “In zoos forever, whether it’s polar bears, brown bears or sloth bears, it is recommended to feed them as if they were carnivores with a high protein content. When you do that, you kill them slowly.”

In separate experiments, researchers gave giant pandas and sloth bears at various U.S. zoos unlimited amounts of food to learn about their preferences, then recorded the food profiles of their choices.

In collaboration with researchers from Texas A&M University and the Memphis Zoo, feeding trials were conducted on a pair of giant pandas to measure their preference for bamboo. They found that giant pandas preferred the carbohydrate-rich bamboo found in tree stems to the protein-rich leaves. At some points, they used the club almost exclusively – for example, 98% of the time in March. The researchers also analyzed data from five Chinese zoos that had successfully bred giant pandas and again found that high-carbohydrate, low-protein diet.

In a series of feeding trials, six sloth bears at zoos in Cleveland, Little Rock and San Diego were given unlimited amounts of avocado, baked yams, whey and apples. They chose the fat-rich avocado almost exclusively, eating about 88% avocado and 12% yams — and ignoring apples all together. It showed that sloth bears prefer foods with a high fat content, low-carb dietwhich may have a similar composition to their wild diet of termites and ants as well as their eggs and larvae.

It’s also very different from the high-carbohydrate diet they’re usually fed in captivity. Sloth bears, native to India, typically live about 17 years in U.S. zoos, nearly 20 years less than the maximum life span attainable in human care. The most common cause of their death liver cancer.

Researchers saw a similar picture in preliminary research on polar bears which showed that captive polar bears, normally fed a high-protein diet, would mimic a high-fat diet in the wild polar bears if given the opportunity. Polar bears in zoos usually die about 10 years before they should, most often from kidney and liver diseases. These two diseases can develop due to long-term inflammation of these organs, potentially caused by years of poorly balanced nutrition.

The current study, along with previous ones, also shows that when captive bears are given dietary options, they will choose foods that mimic the diet of wild bears.

“Of course, there is a long-held belief that people with PhDs know a lot more than slacker bear or brown bear,” Robbins said. “These bears all began to evolve about 50 million years ago, and as far as that aspect of their diet goes, they know more about it than we do. We are among the first to ask the bears: What do you want to eat? What makes you feel good?”

Robbins, founder of the WSU Bear Center, the only research facility in the U.S. with a grizzly bear population in captivity, has studied bear nutrition for decades. He and his graduate students first began investigating their unbalanced diet during a study in Alaska, watching grizzlies eat salmon. At the time, researchers hypothesized that the famously voracious bears would gorge themselves on salmon, sleep, get up, and eat more salmon.

Instead, they saw bears eat salmon, but then wander off and spend hours finding and eating small berries. Seeing this, Robbins’ lab began to study the diets of grizzly bears housed at the Bear Center and found that they gained the most weight when they were fed a combination of protein, fat and carbohydrates, combined with salmon and berries.

All eight species of bears, or bears, had carnivorous ancestors but have since evolved to eat a wider variety of foods, allowing them to spread over more areas without competing directly with carnivores.

“It just opens up a lot more food resources than just being a regular, high-protein carnivore,” Robbins said.