Evacuees returning to the charred Canadian oil sands city of Fort McMurray next month may have to contend with black bears who have been prowling the streets in search of food.

The bears have wandered into the town in greater numbers since a wildfire forced some 90,000 residents from the area earlier this month.

The animals have sought trash cans, dumpsters, and even thawing freezers rife with food, authorities said.

Brendan Cox, a spokesman for the Alberta’s fish and wildlife enforcement branch, said the bears are “smart and adaptive”.

He added: “They can smell food from kilometres away.

“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 blaze had swelled to more than 500,000 hectares, ruining communities, cutting services and making life even more difficult for a region already struggling against a two-year slump in global crude prices.

The town’s residents are due to start returning to what is left of their homes on 1 June.

Fort McMurray is situated among a popular bear habitat in the forests of Alberta’s north and many of the province’s 40,000 bears will be looking for food after a winter hibernation of nearly six months.

Seven wildlife officials are patrolling the streets on the lookout for the bears.

They are also cleaning up garages and setting traps to catch animals that may be attracted to the town.

Four have been caught so far – two were released into the wild and two were put down.

George Kourounis, who presents the Angry Planet television series, said he had been taking photos of a charred hotel in the town when he came within a few metres of a bear.

He said: “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.”