Archive: Detroit Zoological Society Mourns Loss of Polar Bear Anana

February 8, 2021

ROYAL OAK, Mich., 


Initially, it was thought that Nuka may have caused Anana’s death in February of 2021, but this was not the case. An in-depth review discovered Anana died from advanced heart disease. Analysis of Anana’s heart tissues showed that she experienced acute heart failure or a fatal arrhythmia before or during breeding attempts. It was impossible to know that she had a cardiac condition called multifocal myocardial fibrosis, as she showed no clinical signs, and a 2020 medical examination noted no abnormalities in her heart function. Wounds on Anana likely resulted from Nuka holding her with his teeth, as is typical during polar bear breeding. He was also observed moving her around the habitat after she became unresponsive, possibly because he was confused by her behavior.


A female polar bear at the Detroit Zoo was killed by the Zoo’s adult male bear on Monday, February 8, 2021. 20-year-old Anana died when 16-year-old male Nuka was attempting to breed her. According to Detroit Zoological Society Chief Life Sciences Officer Scott Carter, the two bears had lived together without incident in 2020. “This was completely unexpected and the Detroit Zoo staff is devastated by the loss of Anana in this sudden and tragic event,” Carter said. The Detroit Zoo has not experienced the killing of one animal by another animal in decades; the last occurrence was also with polar bears in 1988.

After being apart for several months, Nuka and Anana were re-introduced last week as part of the Association of Zoos & Aquariums (AZA) Polar Bear Species Survival Plan, a cooperative population management and conservation program that helps ensure the sustainability of healthy captive animal populations. This program is vital to sustaining this endangered species and can result in successes like the recent birth of twin cubs, fathered by Nuka at the Detroit Zoo. Currently there are only about 55 polar bears in 25 AZA-accredited zoos and aquariums.

Nuka has lived at the Detroit Zoo since 2011 and has lived with, and bred with, several other female bears without showing harmful behavior. Anana came to the Detroit Zoo in January, 2020, and was introduced to Nuka at the end of March. The Detroit Zoo’s other adult female polar bear, Suka, is in a private maternity den with one of her cubs.