Should Polar Bears Be Locked Up in Zoos?

Twin polar bear cubs Boris, left, and Natasha investigate their surroundings under the watchful eye of their mother, Voda, at the Denver Zoo on March 15, 1999. Ben Williamson writes that polar bears are particularly ill-suited to life behind bars. This is a species that can thrive only in enormous Arctic expanses with vast open water—which no zoo can come close to providing. Gary Caskey/reuters

Earlier this year, when SeaWorld announced that it would separate longtime polar bear companions Szenja and Snowflake so the latter could be shipped off to Pittsburgh to breed whether she wanted to or not, thousands asked the theme park not to do it. Unmoved, SeaWorld sent Snowflake on her way.

Now, just weeks after losing her friend, Szenja is dead.

The pair had been together for 20 years. Is there any doubt that Szenja's heart was broken at the loss of her only companion? Maybe it just felt easier to give up and let go.

Polar bears are particularly ill-suited to life behind bars. This is a species that can thrive only in enormous Arctic expanses with vast open water—which no zoo can come close to providing. They need to roam and hunt and swim.

An Oxford University study found that typical polar bear enclosures are about one-millionth the size of their minimum home range in nature.

Polar bears are designed for the cold. Their thick fur prevents almost all heat loss. They are adept swimmers, and their forepaws act as large paddles, and their hind paws serve as rudders. Mothers are fiercely protective of their cubs, and during the first months after cubs are born, mothers don't eat or drink. Their only purpose is to provide for their little ones.

Dozens of polar bears have died in U.S. zoos (not including those who died in utero), many far short of their expected life spans. The causes have ranged from fights with cagemates to bad reactions to anesthesia.

Some have perished in agony after eating debris thrown into their cages. One died after contracting the mosquito-borne West Nile virus, and another died of salmonella poisoning. Like the gorilla Harambe, one bear was shot and killed after a visitor climbed into the animal's cage.

Related: The death of Harambe: Don't blame the parents

Captive polar bears quickly develop abnormal and neurotic behavior in captivity, from swimming endless laps day and night to nonstop pacing. For those who are provided with some kind of natural substrate rather than just concrete, one can see the actual paw impressions in the soil where they step in the same spot over and over again.

Some zoos have resorted to giving bears anti-depressants to try to curb their anxiety.

Who can forget Gus, one of the polar bears in the Central Park Zoo, who started compulsively swimming figure eights in his pool for up to 12 hours a day, every day, for months? After his companion died, a depressed Gus nearly shut down. He was finally euthanized.

How can zoos justify continuing to imprison a species that requires drugs to mask the evidence of their unhappiness?

And of course, there was Knut, the darling of the zoo world, who had his own line of merchandise and drew people to the Berlin Zoo. He attained celebrity status, even making the cover of Vanity Fair. Yet, when only 4 years old, he had a seizure and collapsed into his enclosure's moat—as horrified visitors watched—and drowned.

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Whether or not the necropsy results are ever released to the public (they often aren't in such cases, unless it's to exonerate the keeper), Szenja died on SeaWorld's watch.

Keeping polar bears in captivity won't save them. If the long-term survival of this imperiled species is to be assured, the zoo and scientific community must commit time, resources and expertise to finding real-world solutions to reducing greenhouse gases and preserving Arctic sea ice instead of squandering money on breeding more polar bears to keep in cages.

Ben Williamson is the senior international media director of People for the Ethical Treatment of Animals.