Zoo animals need to slim down

RALEIGH -- Even hippos and whales, it turns out, can get fat. But how can you tell, let alone slim one down?

Obesity among zoo animals is such a complex problem that zoo nutritionists, scientists and others, from as far away as England, gathered at N.C. State University on Friday for a two-day symposium on such weighty matters as how to tell when an oyster's weight is about right.

"It's actually a huge problem, and a multifaceted one," said Michael Stoskopf, a professor at the college. "You have to look at not only diets themselves and the amount of calories delivered, but also things like exercise."

The basic cause of chubbiness is no different for moray eels and wildebeests than for humans: "If the energy going in exceeds the energy going out, you're going to get fat," said Karen Lisi, a nutritionist at the Smithsonian National Zoological Park. "We don't like to hear that, but that's pretty much how it is for us, too."

With so much variation among creatures, though, nutritionists have to treat the diet of each species almost like an individual scientific study, determining what it eats in the wild and how best to approximate it in captivity, said Richard Bergl, curator of conservation and research at the N.C. Zoological Park in Asheboro.

"It's not just a matter of throwing a bucket of apples in with the monkeys and a bale of hay to the elephant," Bergl said.

When your zoo has hundreds of creatures as different as tree frogs, fish, birds and elephants, the task can be overwhelming.

Even among birds, the variation in diet is huge, what with hummingbirds that sip nectar, fruit-eating parrots and vultures that chow down on rotted meat. The diet for individual animals may have to be adjusted to compensate for changes such as pregnancy, lactation or simply aging, Lisi said.

Her zoo, with about 400 species and 2,000 individual animals, has its own nutrition lab.

Even simply determining whether an animal is overweight is so complex that part of the symposium was dedicated solely to that topic. Sometimes it's obvious when an animal is morbidly obese, Lisi said. Other times, though, a quirk of a given species, such as thick fur, makes it more difficult, and zoo staff might not be able to tell without tranquilizing it and checking by hand.

Biscuits can mean neurosis

Bergl of the N.C. Zoo is an expert on a rare kind of lowland gorilla and spoke on gorilla nutrition Friday. Captive gorillas can get fat for reasons similar to the boom in human obesity, he said in an interview. Humans haven't evolved to handle the huge amount of calories and fat that many are now eating. Similarly, gorillas in the wild live on a bulky, low-calorie diet of such things as leaves, shoots and bark, but in zoos are often fed specially formulated biscuits.

The biscuits offer nutrition, but aren't bulky and don't fill up a peckish gorilla. That stresses out the primates and can lead to neurotic behavior. That also means that zoo gorillas -- who spend much of the day foraging in the wild -- have little to do, except sit around and look bored, the gorilla equivalent of hanging out on the sofa watching TV all day.

Bergl spoke about four gorillas at the zoo that have been on a no-biscuit diet heavy in vegetables such as kale, cabbage and carrots for a few months. For some of the gorillas, this meant a change from about 30 pounds of high-calorie food a day to more than 100 pounds of low-calorie chow.

It's too early to evaluate the health aspects, but their behavior has improved, he said. They're more active now, and no longer sit around with blank expressions.