An effort to train three grizzly bears how to be a bit wilder in Glacier National Park commenced on Friday in the Pitamakan Pass area.

The "aversive conditioning" approach prompted the closure of several trails.

"Closing the trail is necessary to ensure that the aversive conditioning can be conducted in a controlled environment, without interrupting or altering the management actions due to hiker activity," a park press release states. "It will also allow the bears' response to be carefully monitored."

The bears in question were an adult female and her two yearling cubs, a family group that has shown a lack of fear around humans. The female was captured and fitted with a radio collar last week after the bears had demonstrated their habituated behavior on several occasions.

Aversive conditioning involves the use of Karelian bear dogs, along with cracker shells, bean bags or rubber bullets fired from shotguns, to condition bears to avoid humans. The methods have proven to be effective by bear managers in Montana and elsewhere. The Glacier effort is being led by Carrie Hunt of the Wind River Bear Institute.

Because the approach involves dogs to haze wildlife in a national park, it required special approval from Glacier Superintendent Mick Holm.

Breeding female grizzlies are considered extremely important to the effort to recover the grizzly population along the northern Continental Divide.

Trail closures prompted by the effort in Glacier include: the Pitamakan Pass Trail from the Dry Fork junction to the junction with Cut Bank Pass and the Cut Bank Valley Trail from the Triple Divide junction to Pitamakan Pass.

Dawson Pass to Pitamakan Overlook and the Cut Bank Pass will remain open to hikers.