ROYAL OAK, Mich. (AP) — A male polar bear killed a 20-year-old female polar bear at the Detroit Zoo when he attempted to mate, officials said.

“This was completely unexpected and the Detroit Zoo staff is devastated by the loss of Anana in this sudden and tragic event,” said Scott Carter, the zoo’s chief life sciences officer.

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Nuka killed Anana on Monday after being apart for several months, the zoo said.

Nuka, who is 16 years old, has lived at the zoo since 2011 and bred with other bears without harmful behavior, the zoo said. Anana arrived at the zoo in suburban Detroit in January 2020 and was introduced to Nuka a few months later.

The mating program “is vital to sustaining this endangered species and can result in successes like the recent birth of twin cubs” fathered by Nuka, the zoo said.

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