GUS IS DOING THE BACKSTROKE IN A DEEP BLUE POOL IN THE zoo in New York City's Central Park. He pushes off the artificial rock with his hind paw, takes several powerful strokes, then does a diving flip by the underwater window. Then he does it again. And again. And again—on into the evening.

No one knows exactly what Gus, a polar bear, has in mind as he completes his laps in mesmerizing repetitions. But to some of his many visitors, it looked suspiciously like an obsessive-compulsive disorder. Gus's keepers were so concerned that they hired a shrink of sorts: animal-behavior specialist Tim Desmond of Ventura, Calif. Says Desmond: "The swimming began to raise real questions about the quality of his life."

Desmond, 45, who trained the orca, Keiko, that appeared in Free Willy, determined that Gus wasn't "getting all the behavioral opportunities he needs." In other words, the bear was bored. On Desmond's advice, keepers now hide toys and food in the rocks and caves of the 5,000-square-foot enclosure that Gus, 8, shares with female companions Ida and Lilly. "Bears need to work for their food," Desmond explains.

Gus, of course, wasn't always thus. He was a happy, normal cub, growing up in the Toledo Zoological Gardens in Ohio. It took a 1988 move to New York City—where neurosis is worn as a badge of honor—to bring out the richer aspects of his personality.

Desmond says Gus's therapy will continue for the rest of the 700-pounder's life, which could be 20 years or more. No matter, the hide-and-seek ritual has made him a star. "Gus has struck some sort of chord," says zoo spokeswoman Allison Power. "It is a problem people seem to relate to."