Polar bears, cheetah, tigers and other large carnivores with huge ranges just aren't being cared for well enough in captivity, a study published in Nature says, and the authors think that zoos either need to seriously rethink their habitats for these big animals, or phase them out for smaller, easier to satisfy creatures.
For example, polar bears have ranges that cover hundreds of miles of territory in the Artic but are generally kept in small, tank and rock environments which are a million times smaller. They also are notorious for behavioral problems and health problems related to captivity stress, problems that the research said can be predicted because of the large space they need.
Zoos counter that this is "nothing new" and that they're constantly working to enrich the enviroment of animals to help them adjust to captivity.