Polar bear at Calgary Zoo died by drowning following 'crushing' injury

WARNING: Details in story are graphic and may be disturbing to some readers...

The Wilder Institute/Calgary Zoo has revealed the cause of death for polar bear Baffin last week.

The zoo said seven-year-old Baffin had been sparring with eight-year-old polar bear Siku in the pool in their enclosure on Friday, but went under the water and failed to resurface.

On Monday, following a necropsy, the zoo announced Baffin died by drowning following a "crushing injury to his trachea" by Siku during the "rough play."

Officials presume Baffin lost consciousness under the water due to his injury, and subsequently drowned.

"We believe it was a bite," Dr. Sandie Black, senior veterinarian, said, saying it squeezed and cracked one of the bear's trachea rings.

Black said Baffin's skin was undamaged, and there was only a very small amount of bruising visible on the inside.

"Had this been on land, it would have been very different," she said, calling the incident a "tragic accident."

The necropsy – which was completed by an independent pathologist as well as the zoo’s animal health team – also confirmed Baffin was in excellent physical condition.

Additionally, officials say the necropsy found no evidence of heat-related stress.

Black said the necropsy results offer "hollow comfort" to the team at the Calgary zoo – and the team at Assiniboine Park Zoo, where the bears lived before coming to Calgary in October 2023.

Baffin was rescued as a cub when he was less than a year old.

Siku had been rescued as an orphan cub in 2016.

"Baffin and Siku shared a long history as habitat mates, and the enjoyed a companionate relationship, which is why they were chosen to come to Calgary," Black said.

She said the bears "played daily," both in and out of the water.

"The type and intensity of play on the day of the incident appeared to be no different than the type of play their caregivers witnessed from them on a daily basis."

Black says they have no immediate concerns about Siku, who is doing "well" and has a good appetite.

Black says they are monitoring Siku as he mourns the loss of his companion, and says there is a possibility of bringing in another polar bear to join him in the future, but nothing immediately.

"Certainly we would like, for his welfare, to bring another polar bear – at least one more polar bear – into the exhibit, but there's no pressing need to do so."

Black said in captivity, polar bears can live "up to about 30 years."

She said that due to the accidental nature of the incident, there are no plans to change the polar bear habitat at this time.

"It's been really tragic for us and our team," said Colleen Baird, director of animal care, health and welfare.

"Hearing all the well wishes and condolences have really helped us get through it."