Winter storms can have a profound impact on humans and animals alike. In today’s installment of Carolina Curious, WFDD’s David Ford looks into how North Carolina’s avian wildlife adapts in the bitter cold.
There are lots of ways birds cope with the freezing temperatures, beginning with their diet. North Carolina Wildlife Extension Biologist Falyn Owens says in the winter, they switch from a high-protein diet of insects to fattier food like seeds.
“And they can eat that seed, and they can maintain their energy reserves so that they can keep their bodies warm through the cold winter months,” says Owens.
She adds that if food is scarce, some birds just pack up and leave; they migrate to warmer regions with better dining options. Others, like the tiny hummingbird, will change their behavior by going into a semi-state of dormancy known as torpor. It’s similar to hibernation but not quite as deep.
And there are physiological adaptations as well. Birds have a unique mechanism that allows them to keep warm, even when the outside temperatures are really cold: feathers.
Owens says a lot of people don't realize the insulating power that feathers have: fluffy on the inside, but waterproof and windproof on the outside — like a double-paned window.
"It's not the glass that's providing the insulation," she says. "It's actually the pocket of air that's captured in between the panes of glass. So bird feathers do the same thing. Essentially, their skin is like one pane of glass. The downy layer of their feathers is like the air pocket. And then the outside layer of their feathers are going to be the other pane. And it's that air pocket that really is what's providing the insulation and keeping them warm."
She says if you see a bird in the bitter cold that looks all puffed up and fat, they're actually not fat at all, but they are intentionally poofing out their feathers as a way of creating a bigger air pocket underneath them that keeps them warmer in the cold.
But what about those featherless feet? Don’t they get frostbite?
"They actually have a circulatory adaptation where their blood vessels are parallel to one another, and as the warm blood from their heart gets pumped into their legs toward their feet, they actually will sort of drop the warmth into the blood that's going back towards their heart that's already been to their feet," says Owens.
So, the blood warms up before it goes back into their body. As for the bird’s feet, Owens says those do get really, really cold, but it doesn’t hurt them, and they’ll be just fine.