An increase in the number of encounters between polar bears and people in Churchill, Man., over the last three years means more of the animals are being temporarily housed in a holding facility known as the “polar bear jail.”

The CBC reported that polar bear activity reports kept by the government of Manitoba show that the number of documented cases of human-polar bear encounters in Churchill increased from 229 in 2013 to 351 in 2015, while the number of bears captured and held at the jail before being released back into the wild jumped from 36 in 2013 to 65 in 2015.

Manitoba conservation officers have been boosting their patrols along the shore of Hudson Bay, where many polar bears have been encountered and captured.

In winter, polar bears hunt on sea ice for food that will sustain them during spring and summer. But with Arctic waters freezing later and thawing earlier, bears are forced to spend more time on land, where encounters with people are more likely.

“What’s the tipping point?” Daryll Hedman, a regional wildlife manager for Manitoba Conservation, told CBC. “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, a polar bear expert at the University of Alberta, told CBC that as the bears spend more time on land without food, the animals would increasingly venture 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.”