• Anana, 20, was killed by Nuka, 16 during a breeding session
  • The male bear earlier mated with other female bears without showing harmful behavior
  • The bears were re-introduced to each other last week as part of zoo’s polar bear survival plan

A female polar bear at the Detroit zoo was killed by a male polar bear during a breeding session Monday, zoo authorities said.

The 20-year-old female bear, Anana, died when a 16-year-old male bear, Nuka, was attempting to mate with her, Fox 2 Detroit reported, citing a news release from Detroit Zoological Society.

The two bears lived together "without incident" since 2020, according to the Detroit Zoological Society's Chief Life Sciences Officer Scott Carter.

Carter said in the release that Anana’s death shocked the zoo staff.

"This was completely unexpected and the Detroit Zoo staff is devastated by the loss of Anana in this sudden and tragic event," the outlet quoted Carter, as saying.

Anana’s killing is the first instance of one animal killing another in the zoo in decades. The last incident which occurred in 1988 also involved polar bears, the publication reported.

After spending months apart, Anana and Nuka were re-introduced to each other last week as part of the Association of Zoos & Aquariums (AZA) Polar Bear Species Survival Plan. The plan aims to sustain endangered species, ABC-affiliated WXYZ-TV reported.

Nuka had successfully fathered two polar bear cubs recently after a breeding session with another polar bear, according to WXYZ-TV. Nuka has been living in the zoo since 2011 and has bred with several other female polar bears without causing them any harm.

Currently, the zoo reportedly houses about 55 polar bears in 25 AZA-accredited zoos and aquariums.

In December 2019, a polar bear died at Sea World theme park, Queensland, Australia due to unknown reasons. The 19-year-old polar bear, Liya, was born in Russia and was transported to Sea World as part of an international breeding program in 2001. Liya lived in the zoo for nearly two decades and was a magnet to tourists.

A polar bear can live up to 20 to 30 years. These animals are internationally listed as vulnerable species by the International Union For Conservation Of Nature (IUCN). Apart from this, the species is listed under a variety of classifications depending on international, national, and regional regulations.

Polar bears are on a glide path towards extinction, according to a recent study. 
Polar bears are on a glide path towards extinction, according to a recent study.  POLAR BEARS INTERNATIONAL / Kt MILLER