Manitoba government documents suggest polar bear encounters with people have reached record levels on the shores of Hudson Bay with more of the mammals ending up in a specialized jail in Churchill.
Polar bear activity reports from the past three years show the number of documented cases in Churchill has jumped from 229 in 2013 to 351 last year.
The number of bears that were tranquilized and housed in the town's holding facility — known as the polar bear jail — before being released into the wild almost doubled from 36 in 2013 to 65 last year.
Daryll Hedman, regional wildlife manager for Manitoba Conservation, said last year set a record for the number of polar bears caught within the populated "control zone" of Churchill.
"Three hundred and fifty-one — for occurrences, that's a high number," he said.
While Manitoba conservation officers have stepped up their patrols recently, Hedman and other experts say climate change is largely to blame.
Canada is home to two-thirds of the world's polar bears, but experts say climate change could make the Hudson Bay population extinct within a few decades.
Polar bears depend on winter hunting to build up enough fat to carry them through the lean summer months on land when food is scarce. But Arctic waters now don't often freeze up until early December and thaw much earlier in the spring. That leaves polar bears with less time to bulk up on fatty seal meat while on the ice.
As the bears spend more time on land with less fat, they grow hungry and can venture into town in search of food. Where the first encounters with polar bears used to be late August, Hedman said polar bears are now coming into contact with people as early as July 1.
"What's the tipping point?" he said. "What's the threshold that they can go without food? When they're on land, they're not eating.
"How long can they sustain themselves without getting onto that sea ice platform to hunt seals again?"
Andrew Derocher, one of the country's leading polar bear experts based at the University of Alberta, said the population is in "grave condition." The population has stabilized around 800 bears but few cubs are surviving past the first year, he said.
As they spend more time on land without food, Derocher said they could venture more and more into populated areas.
"Hungry bears are always going to be a problem," he said. "All projections are that they will increase their on-land time."
When the ice does finally form on Hudson Bay, Derocher said it's freezing up further afield so polar bears often have no choice but to go through populated areas to get on it.
"It's a response to changing ice conditions," Derocher said.
Peter Ewins, a senior officer with the World Wildlife Fund, compared the increase in polar bear encounters with raccoons in larger cities. Those who learn to break into homes and garbage cans are the hungry ones bent on survival, he said.
"The portion of your total (polar bear) population that's nutritionally stressed is just going to go up the less access they have to fat-rich seals," Ewins said. "Until we solve the climate change thing, this isn't really going to be a good situation. It's just going to get tougher."