The Columbus Zoo and Aquarium says two of their female polar bears are likely pregnant.
The Columbus Dispatch reports that the two will be moved to "maternity suites," which have been built away from the exhibit.
The lone male bear was seen breeding with twin females earlier this year.
There are no polar-bear pregnancy tests, so zookeepers rely on clues.
Zoo spokeswoman Patty Peters told the newspaper that they include seeing the twins add weight.
The animals also become pickier about what they eat and become more hostile.
Polar bears have been born at the zoo twice, in 1984 and 1988.
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