the animals are kept together in small spaces with no privacy and little opportunity for mental stimulation or physical exercise This results in abnormal and self-destructive behavior called zoochosis A worldwide study of zoos conducted by the Born Free foundation revealed that zoochosis is common among animals kept in small spaces or cages Another study found that elephants spend 22 percent of their time engaging in abnormal behaviors such as repeated head movement or biting cage bars and bears spend 30 percent of their time walking back and forth a sign of distress