How Will Chicago’s Birds Weather the Polar Vortex?

Here’s how the region’s avian residents will survive the cold snap.

BY JESSICA LEIGH HESTER 

JANUARY 30, 2019

How Will Chicago's Birds Weather the Polar Vortex?

CHICAGO IS SHUDDERING. With temperatures dropping down to -20 degrees Fahrenheit (colder, with the windchill), school is canceled, museums are closed, and transit agencies are relying on flaming, kerosene-soaked ropes to warm up steel tracks. The temperatures are life-threatening, and several 24-hour warming sheltersare open. Humans are trying their best to hunker down, but what are the region’s birds supposed to do?

Though the city’s feathered denizens can die in the subzero temperatures—from hypothermia or starvation, if their food sources are locked up in frozen bodies of water—many are generally equipped to handle at least a short burst of bracing cold.

Some of Chicago’s wintertime residents have popped down from their breeding grounds in the Arctic—snowy owls, common redpolls, and snow buntings are known to drop by the Windy City in the cold months, says Alexandra Anderson, a graduate student in environmental and life sciences at Trent University, who studies Arctic birds. “These species may be able to tolerate colder temperatures than other species,” Anderson says. The current temperatures are the harshest that many of the city’s other avian urbanites have seen in their lifetimes—but even so, any bird that winters in Chicago is accustomed to heavy snow and fierce wind. “Species that spend the winter regularly in the region have evolved lots of different ways to deal with these cold snaps,” says John Bates, associate curator of birds at the Field Museum of Natural History in Chicago.

They’ve already got cozy coats, for one thing. “Every bird is walking around wearing a down sleeping bag,” says Kevin McGowan, a behavioral ecologist at the Cornell Lab of Ornithology. When temperatures plummet, birds will “stay the heck out of the wind,” McGowan says, and fluff up their feathers to trap air inside. Their body heat keeps the air pocket warm, and the birds carry their insulation with them like a little portable space heater. “I guarantee you every bird you see in Chicago is going to look fat,” McGowan says. “But they’re not—they’re just cold.” They’ll probably also find the warmest crannies they can—up in the the cavities or branches of a tree, close to puffing chimneys, or on window ledges, away from the strongest gusts.

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