The 20-year-old female Anana and the 16-year-old male Nuka lived together without incidents in 2020, and zoo officials say they are surprised and destroy what happened.
“This was completely unexpected and the staff at the Detroit Zoo will be devastated by the loss of Anana,” Scott Carter, chief of life sciences at the Detroit Zoological Society, said in a statement.
According to the zoological society, Nuka lived in the zoo for 10 years without ever engaging in harmful behavior with polar bears.
Anana has lived in the zoo for just over a year. The bears were brought back last week after several months of separation as part of a conservation program to protect endangered species.
The program says recently born twin puppies whose parents are Nuka and 8-year-old Suka according to the organization.
An animal was last killed in the zoo in 1988. This case also involved polar bears, the statement said.