CHICAGO – When red pandas go on exhibit for the first time at Brookfield Zoo in July, they'll be housed around a broad tree that looks like a giant bonsai and has magical qualities. At semirandom intervals throughout the day, food will drop automatically into stainless steel cups expertly fitted into what look like huge knotholes in the "tree," a construction of welded metal, plastic mesh and concrete.

The red pandas — telegenic, frequently erect-standing relatives to raccoons, rather than to bears or giant pandas — will learn that the cups sometimes contain food, sometimes not. In this way, the theory goes, they'll also stay metaphorically on their toes, engaged with their environment and steadily on the hunt for sustenance.

"Now the habitat provides, instead of the keeper," said Tim Sullivan, the zoo's curator of behavioral husbandry. "Food can appear, like in the wild."

Sullivan is helping to lead what he calls a paradigm shift at Brookfield, a revolution in the way its residents eat that is proving to have benefits for guests and animals alike. Instead of the old regimen of keepers delivering food two or three times a day on a schedule, the zoo is working to propagate semirandom feeding devices throughout its 216-acre property in the near western suburbs. It's being used in 15 to 20 percent of exhibits now, but the goal is to get to near-blanket coverage within five years. "The story is always the same: We give the animals something else to do, and they're more than happy to do it," Sullivan said.

The result, in anecdotal observation and in two scientific papers Brookfield zoologists have authored, has been more active animals, which has equated to visitors spending more time in front of the animals. "When an animal's in the wild, the first thing it does in the morning, it says, you know, 'I've got to find food.' And it doesn't get that 8:30 in the morning and 4 in the evening feeding," said Bill Zeigler, the zoo's senior vice president of animal programs. Such food drops can bookend a sort of torpor that produces, Zeigler said, a "couch-potato mentality."