Baffin, the Wilder Institute/Calgary Zoo’s 7-year-old polar bear, was found to have died on July 19 as a result of an accident during play with Siku, the zoo’s second polar bear.

An extensive necropsy performed by an independent wildlife pathologist along with the zoo’s Animal Health Team found that Baffin had his trachea crushed by Siku during rough play underwater, leading to his drowning death in the lower pool of the polar bear conservation enclosure.

In mammals, trachea are more colloquially known as windpipes, and is a tube that connects the larynx at the top of the neck to the bronchi of the lungs allowing for the flow of air into the lungs.

Dr. Sandie Black, Senior Veterinarian at the Wilder Institute/Calgary Zoo, said that Baffin was presumed to have lost consciousness underwater due to the tracheal injury.

“It was it was a combination of those two things: the bite happening underwater and whatever happened to Baffin in the moment of that grab… had this been on land it would have been very different,” Dr. Black said.

Colleen Baird, Director of Animal Care and Health and Wellness for the Wilder Institute/Calgary Zoo said that the depth of the pool that the bears were playing in did not make a difference, rather it was the presence of water and the injury alone that led to the tragic death.

“It doesn’t matter really how deep the pool is. The tragic accident happened and it would happen if there was a foot of water or the full pool was filled out,” she said.

Rough play, said Dr. Black was normal between the bears, and that polar bears have thick layers of fat and skin that would have normally otherwise prevented an injury from occurring.

“They have incredibly thick skin, and it’s it’s typical of how they play. If you think about how dogs roughhouse, very much mouthing and going at each other in that way. We believe this was just very tragically a misplaced grab and a reaction to that underwater,” Black said.

She said that during the necropsy, an extensive examination of Baffin was performed and the injury to his trachea was the only detail that stood out as a potential cause for his death.

“We look at muscle, we look at the skeleton, we look at all the organs, and examine those in detail looking for anything that doesn’t fit—that is outside of normal. And really in Baffin and the only thing that was outside of normal was this evidence of of injury in his neck,” Black said.

“We don’t always find an obvious cause of death, but this one was very obvious: that tracheal damage and then the evidence of drowning.”

As a result of the outcome of the investigation, and the accidental nature of the death, the zoo said they would not be looking at making changes to the polar bear enclosure.

Outcry of support for zoo community

Baird said that the reaction from the Calgary community for the zoo community has been one of support.

“Hearing all the well wishes and condolences have really helped us get through it. Of course, we have some people that maybe are critical toward that. Those voices are quieter, and we just appreciate everybody’s care,” she said.

In contrast to the tragic accidental death of Baffin, she outlined what would have occurred to both bears had they not been taken into human care in Manitoba.

“They wouldn’t have survived,” Baird said.

“Polar bears need to be taught several things by their mum as they’re growing up. They usually spend two to three years with their maternal mother. These bears were abandoned when they were under a year old, and they would not have survived.”

Both Baffin and Siku were taken to the Leatherdale International Polar Conservation Centre at the Assiniboine Park Zoo in 2017, before being moved to the Calgary Zoo in 2023.

Both bears were long-time habitat mates at the Assiniboine Park Zoo, and that was a major reason for both zoos to consider moving them to Calgary’s habitat.

Baird said that Siku was being monitored for behavioural changes, but that it was also important to not anthropomorphize the behaviour of the bears.

Siku was said to have been observed to notice that Baffin was missing from the enclosure, but that behaviourally was not mourning the loss of Baffin in the way that people or pets like dogs would.

“We are monitoring him and we are observing his behaviours. He is participating in training sessions. He is shifting in and out, he’s healthfully eating all of his diet. So, outwardly he’s not showing any stressors at this time,” Baird said.

The zoo said that there isn’t any immediate need to add another polar bear to the enclosure for the health of Siku, and that given the nature of Baffin’s death they would be carefully considering the next steps. Baird said, however, they Re committed to bear conservation.

“We have great relationships with a Assiniboine Park Zoo. We’ll have conversations around personalities, and they know this bear well. They’ll help us make those decisions,” said Baird.

“We will have probably some concerns because of this incident, but it’s such a rare and like Dr. Sandie was saying, just an unusual moment… we think that it’s better better for Siku that we do give him some other things mentally to think about.”