People who are against zoos argue that even the biggest enclosures aren’t big enough for many animals. Polar bears might walk or swim up to 100 miles a day in the wild. In zoos, they often live in an area about the size of a school gym.
Many animals also need more company. In the wild, elephants live in big family groups. But in zoos, they often live in pairs—or alone. More than 25 U.S. zoos have changed that. They sent their elephants to sanctuaries, where the animals live in large groups. But at other zoos, loneliness is still an issue.
Life in captivity can be hard for large animals. Many show signs of being lonely, bored, and sad.
“When you see a tiger pacing back and forth, that is a very stressed tiger,” says Lori Marino, a scientist who studies animal behavior.