Evacuees preparing to return to their homes in the burnt city of Fort McMurray, Alberta, have been warned of a new threat, in the form wild black bears who have roamed into the deserted city in search of food, it was reported on Saturday, 21 May.

The bears are a native species to the surrounding north Alberta area – a forested land that holds an estimated 40,000 of the species – but reports have stated that bears are prowling in higher numbers inside the city, following the evacuation of 90,000 residents from the Canadian oils sands city.

On 20 May rain and cooler weather helped to contain the blaze, although heavy smoke is causing concern for the authorities ahead of the 1 June move-in date. So far, oil sands such as Imperial Oil, StatOil and ConocoPhillips Canada are back in operation.

According to reports from by Sky News, the bears have been rooting through trash cans, bins and thawing freezers that are stocked up with food provisions.

Alberta's Fish and Wildlife spokesperson Brendan Cox, said that the bears are smart enough to be able to adapt to their surroundings.

"They can smell food from kilometres away," he explained. "Just as you and I go to the nearby grocery store, or our favourite restaurant, the bears continue to return to a particular food source."

The rise in bear numbers has been seen as a potential threat to those moving back to what is left of the city from 1 June. The blaze consumed 500,000 hectares of land, destroying communities, services and wildlife in its path since the fire sparked on 4 May, 2016.

Alberta wildfire
Canadian Prime Minister Justin Trudeau and Fort McMurray Fire Chief Darby Allen (R) look over a burnt out car while visiting neighbourhoods devastated by the wildfire that forced the evacuation of the city in Fort McMurray, Alberta, Canada Reuters

According to further reports, seven wildlife officials are patrolling the streets of Fort McMurray and have allegedly caught four of the animals. Two were reportedly released back into the wild, while the other were euthanised

George Kourounis, a presenter of the Angry Planet TV series, described what he saw when was out taking photos of charred building remains when he came into close to a bear: "I spotted something moving out of the corner of my eye and that something was a great big black bear looking for food in this dumpster just outside the hotel. It was crazy."