Inside Parks Canada's unsuccessful efforts to capture an escaped bison bull

Wild plains bison cross the Panther River in Banff National Park in a handout photo. (THE CANADIAN PRESS/HO - Parks Canada, Dan Rafia)

The bison bull was a long way from where he should have been -- on provincial grazing lands in west-central Alberta instead of the rugged backcountry of Banff National Park.

"We are considering destruction versus capture of this animal," Parks Canada wildlife ecologist Jesse Whittington wrote 11 days after the bull, dubbed M05, crossed the park's eastern boundary.

Emails obtained by The Canadian Press under the Access to Information Act detail how Parks Canada staff strived to bring MO5's summer excursion to a happy conclusion, and how they carefully crafted their message when it did not turn out the way they'd hoped.

A Parks Canada program to reintroduce bison to Banff reached a major milestone July 29 when more than 30 animals were released from a paddock into 1,200 square kilometres of Rocky Mountain wilderness. It was the first time in 140 years that bison roamed wild there.

About a week later, two bulls -- M05 and M19 -- ventured out of the park independently.

The agency committed to the Alberta government that it would take action if bison wandered too far. Public safety was a factor and there were also concerns about the animals coming into contact with cattle or damaging property.

For days, staff were able to track the bulls' movements using satellite data and signals from their collars.

By Aug. 16, M05 was covering an average of 15 kilometres daily and could have reached private ranchland within a day.

They tried coaxing it back into the park, but it didn't work. Moving him was not an option because of a wildfire nearby. Fire crews were using all available large helicopters.

Parks staff found M05 in a swamp and shot him.

"That was a thankless and difficult job. I appreciate your willingness to do it," Whittington wrote the two workers who killed the bull.

M19 was still outside the park, but his location was not a concern at the time.

Karsten Heuer, manager for the Banff Reintroduction Project, told colleagues it was important to get the tone right in a media release.

"Minimize repetition and avoid use of government terms like 'management action' that make us sound a little cold-hearted."

Once the bull's death did hit the news, the agency noted "overwhelmingly negative" reaction.

"The CBC and CTV Calgary Facebook posts both garnered over 100 comments, over 100 'angry' reactions and over or nearly 100 'sad' reactions," said a report that included a sampling of comments.

"Parks Canada you screwed up royally. You don't deserve bison roaming free in the park," one said.

Staff at the agency's national office sent supportive messages to their Banff colleagues.

"We just want to sympathize with you on the occasion of what must have been an agonizing decision," said one note to Heuer.

Parks officials were able to capture M19 three days after M05 was killed.

He was tranquilized, hoisted away by helicopter and then trucked to Waterton Lakes National Park. He couldn't return to the Banff herd, lest he wander off again and encourage others to follow.

National office was not keen on publicizing a photo of M19 bundled up and suspended under the helicopter. It said it would "prefer having a picture of the bison (happy and healthy) in his new paddock."

"The picture below might be misinterpreted by the public, be shared out of context on social media etc."

In an interview, Bill Hunt, Banff's resource conservation manager, recalled it being a tough time. That was especially true for those who killed M05 as they had spent 18 months caring for the animals before they were released.

"Whether it's dealing with bears or elk or cougars or wolves or bison, sometimes we have to make these difficult decisions," Hunt said.

The remaining herd -- now numbering 34 -- has mostly gathered around the spot where it was initially released. One bull seems to like being on his own the next valley over, but he's still well within the reintroduction zone. A cow and two of her young dipped briefly across the boundary in October, but turned back.

"Although it had some very serious challenges, overall we're having a fantastic outcome here," Hunt said. "Thirty-four healthy bison maintaining themselves over winter, which was our key concern, right in the heart of Banff."