The extremely cold winter is being blamed for killing a variety of waterfowl.

Because 90 per cent of the Great Lakes are covered in ice, deep divers haven't been able to feed on fish and they are starving to death, says a Windsor naturalist.

Birds that are surviving are doing so by migrating to places like the Detroit River and Lake St. Clair, where there has been substantially less ice cover due to frequent ice breaking along shipping routes.

Paul Pratt, a naturalist with the City of Windsor, said he has found birds that normally call the middle of Lake Huron home on the shores of the Detroit River.

Scoters, long-tailed ducks and red-necked grebes are flocking to food sources.

Pratt said a record 50,000 red-necked grebes were spotted on the St. Clair River between Windsor and Sarnia this winter.

"They’re [normally] far from land. We don’t even get to see them," Pratt said.

The birds are known as deep divers, some of which can dive to the bottom of the lake in places.

"These birds are having big trouble," Pratt said. "Food is harder to find with all the deep snow and ice."

Windsor alone saw a record snowfall this winter. More than 242 cm of snow has fallen. The previous record was 225.5.

And it's been extremely and unusually cold this winter. More than 90 per cent of the Great Lakes are covered in ice.

Earlier this year, 15 swans had to be rescued from the icy waters of Windsor's Lakeview Marina.

Several swans were trapped in the ice.

"This is the first time I've ever seen this," said Ted Foreman of Bob's Animal Rescue. "It hasn't been this cold since the winter of '78 and there's no food for them. It's all frozen up. Ducks and geese can go to the corn fields but these [swans] can't."

The swans that survived were taken to Wings Wildlife Rehabilitation Centre in Amherstburg.

"We’re seeing a lot more dead waterfowl than we normally would," Pratt said. "We may have to wait for the breeding season to see the impact on their numbers. It could take 10 years to recover from a winter like this."