A grizzly bear which mauled a woman to death in a rare predatory attack in Montana had become “food-conditioned”.

Leah Davis Lokan, 65, had encountered the bear about an hour before the attack and was able to scare it away, but it returned around 4am and killed her.

Experts believe the bear was attracted to food in and near her tent, as well as smells from recent Independence Day picnics.

A report into the incident was recently published and comes shortly after another fatal grizzly bear attack in the large US state.

Ms Lokan, from California, had been camping in the small town of Ovando, along the banks of the Blackfoot River, made famous by the film A River Runs Through It, on 6 July 2021.

The town borders a huge expanse of forested land that is home to an estimated 1,000 grizzlies.

After the first encounter, she had taken some packaged snack foods and dry lentils out of her tent and retrieved a can of bear spray, the investigation found.

However, her toiletries remained in the tent contained in two bags that had previously held dried blueberries and still smelled like the fruit, investigators said.

A Texas couple camping nearby were awakened just after 4am to noises that indicated Ms Lokan was being attacked.

The man yelled at the bear and deployed his pepper spray after seeing the animal “pouncing up and down” on her and her tent.

The 417-pound (189 kilogram) male grizzly bear broke her neck and severed her spine, an autopsy found, causing instant death.

A nearly empty can of bear spray that appeared to have been recently deployed was found under her tent, officials said.

The bear that mauled Ms Lokan was shot three days later while raiding a chicken coop near Ovando.

“Not all bears exhibiting food-conditioned behaviour exhibit predatory behaviour,” the 28 June report said.

“But for some unknown reason a predatory response was triggered in this bear.

“While foraging under the cover of darkness in Ovando, perhaps due to a simple movement made by the sleeping victim, or a certain sound made by the victim, the bear reacted and ended up taking the life of Ms Lokan.”