ROSEVILLE — This year’s deep snow and extreme cold have taken a toll on Minnesota wildlife — especially swans and other waterfowl that can’t find open water on the state’s many frozen lakes.

The Wildlife Rehabilitation Center of Minnesota is treating birds that have come in with injuries.

Veteran Agnes Hutchinson recently corralled one of about a half dozen of the birds. She said the swans and other birds are having difficulty finding open water.

“They have to stand on ice a lot more than they usually would have to. And that’s really hard on their feet,” Hutchinson said as she wrapped a swan in towels. He “probably got caught without anywhere to go and protect his feet, and he just got frostbitten.”

Center director Phil Jenni said birds are also starving because they can’t find a food source on land. And, when there is no open water, birds are also more vulnerable to attack from raptors and other predators.

All over the Midwest, swans, mallards and even loons have been stranded by the coldest weather in more than 30 years. Rescuers along Lake Michigan in Milwaukee have brought six times as many diving ducks into the Wisconsin Humane Society.

Hutchinson said the center’s staff is doing what they can to get animals back on their feet, such as cutting away dead tissue or giving the birds food.

She applied bag balm to the swan’s feet to keep its skin healthy. Another vet amputated the ends of the swan’s toes and cut away some webbing.

“When he came in, we were discussing, how much of the webbing will we have to take off. How much of the webbing does he need to swim properly?” she said. “But he still has a good amount, so we said we’re going to give him a chance and we’re going to try.”