Field Note: Polar Bear

Female polar bear Anana swimming past underwater viewing window at Lincoln Park Zoo

Anana, Lincoln Park Zoo’s 14-year-old female polar bear, swims past the underwater viewing window at the Polar Bear Plaza exhibit.

Cool Facts About Polar Bears

Will Anana ever get another polar bear to share her habitat?
—Zoo Visitor

Anana, the zoo’s female polar bear, engages scores of guests. Visitors marvel at the 650-pound swimmer as she glides like a submarine through her 266,000-gallon pool. She’s the sole resident of one of the world’s largest polar bear exhibits—and in her case, one is not a lonely number.

Polar bears (Ursus maritimus) are solitary animals. In their Arctic home, individuals exemplify endurance, hunting seals across vast ranges of sea ice and ocean. Encounters with other bears are infrequent.

Mating is an exception to the rule. But even this ritual, which takes place between late winter and early spring, lasts at most a few weeks before the successful breeding pair parts ways. Motherhood is another exception. Moms give birth in winter dens to two cubs about 265 days after mating—a period that includes delayed embryo implantation so the female can conserve energy during warmer weather when ice melts and seals are harder to find. After birth, the small family group remains together for two–three years.

Other kinds of interactions in polar bear society aren’t quite so sociable. Male polar bears battle over the few available females during breeding season; the latter mate only after their cubs disperse. Males attempting to scavenge another bear’s seal kill often instigate a fierce fight, with smaller combatants usually heading away hungry.

Anana, at 14 years old, may still be able to mother cubs. It’s possible she’ll be paired with a male in the future if hormone measurements green-light the option and a breeding recommendation is made by the Polar Bear Species Survival Plan® which manages this vulnerable species’ zoo population.

If and when that day arrives, Anana will keep swimming, dozing in her den behind the scenes and chasing the fishy treats tossed into her pool by keepers. “She’ll chase them down in the pool for exercise,” says Curator of Mammals Mark Kamhout. “Little known fact, though: her favorite treat is peanut butter.”

• Published February 12, 2014 • Originally published in Winter 2013 Lincoln Park Zoo Magazine

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Lincoln Park Zoo magazine Winter 2013 issue

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