Gus, the Star of the Central Park Zoo, is Dead at 27

Farewell to Gus, Whose Issues Made Him a Star. (The New York Times, 8/28/2013)

Excerpt:   Long the popular face of the zoo, even as his lap swimming became less obsessive, Gus began exhibiting a loss of appetite in recent days. He was having trouble chewing. Zoo veterinarians hoped it might be just a bad toothache. But when they examined him on Tuesday afternoon, they found a large inoperable tumor in his thyroid region and decided to euthanize him.
Gus was 27.

Polar Cam at the San Diego Zoo

Polar Bears in Zoo.  (Polar Bears International, an organization  that uses research, education, and action programs to address issues that are endangering polar bears, )

Today, many zoos around the world house polar bears that live in well-designed exhibits far different from the concrete cages of the past. Modern exhibits include rushing waterfalls, chilled pools stocked with fish, enormous swimming pools, and gravel pits where the bears can dig. 

Many zoos also now offer enrichment activities designed to encourage the expression of natural behaviors and play. These activities are good for the bears—and help better engage guests to make changes to help polar bear habitat.