Nick Halter, a Twin Cities reporter at Axios, noticed a peculiar pattern on his morning walks — hundreds of ducks braving subzero temperatures.

Many ducks still fly south for the winter months. But climate data shows Minnesota winters have warmed more than five degrees on average since 1970, creating a more tolerable environment for ducks and other birds.

These ducks are deciding there’s no reason to make the potentially dangerous journey south when Minnesota’s warming climate provides a habitable environment, he said.

“You don’t get as cold, you don’t have as deep of freezes and you have more open water,” said Halter said. Ducks that do stick around have no problem staying warm, Halter said. Insulation from their feathers combined with the counter-current heat exchange manages the temperature of the blood destined for their feet. And the open water provides an ecosystem that makes the decision to stay easier.

“They kind of change their diet in the winter time,” said Halter. “When it’s warm, they’ll eat insects and fish. Then become more vegetarian in the winter time — they’re going to eat roots and seeds — and so the open water does present opportunities for more food, too.”

Climate isn’t the only factor that’s making more ducks want to stay put in Minnesota, Halter said. Evolution and natural selection also play a role.

”Birds that stick around here, and then procreate — their offspring are then sort of naturally selected to not also migrate,” Halter said.

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