It’s that time of year when I marvel at the little songbirds at the birdfeeder outside my kitchen window. They only weigh a few ounces, yet somehow manage to stay warm in freezing temperatures. Then I take a trip down to the lake and really start to shiver. How do birds stay warm in winter?
When I arrive at the partially frozen lake, I notice that some of the geese, ducks, and gulls are standing on the ice, while others are on the ice-free parts of the lake, swimming on the water. Some of them are even diving in between. And somehow they seem to be just fine? Brrrrr.
Birds are a marvel of nature’s engineering (aka evolution). They can be found on every continent, in any habitat, at any elevation, and what I think is the coolest - they can be found down on the ground, up in the air, and under the water.
Let’s go back to our starting point about how they stay warm:
Feathers are nature’s best insulator. Not just any feathers, but the famous down feathers. Our common Canada Goose (Branta canadensis) is known to have some of the best down feathers.
Down feathers are found under the bird’s contour feathers (the visible feathers on a bird’s body). Instead of having barbs that keep feathers nice and smooth by interlocking like velcro, they’re fluffy and soft.
This extremely fine fiber structure is superior in insulation to wool or polyester. Birds are warm-blooded and must regulate their body temperature. That’s where the down feathers come into play: These “formless” feathers trap the air and create a thermal barrier. In addition, they also help with buoyancy in waterfowl.
So that’s how our little friends stay warm out there, as long as they find enough to eat in order to keep their metabolism going.
Now let’s have look at their feet - especially the feet of birds that spend long periods of time standing on ice. Most waterfowl and gulls have webbed feet, which translates into more surface area than un-webbed feet. Keeping their feet warm in winter would require a lot of energy at a time when food is scarce (food = energy). But, as mentioned above, birds are a marvel of nature’s engineering.
These birds minimize their body heat loss by allowing the temperature inside their feet to drop to the actual outside (ambient) temperature. How do they do this? Without getting too technical, the blood vessels in their feet act like a heat exchanger: Blood in the arteries is cooled on its way down to the feet, and then heated up again in the veins on its way back to the heart, through an intricate network of blood vessels. Incredible stuff.
Now, bundle up, go down to your local lake, and see what birds are out there!
If you’re lucky enough to live along a so-called flyway for waterfowl, the end of February until about mid-March is the best time to see the biggest variety of waterfowl species.
But it’s not about just looking for birds. Actually look at the birds. What are they doing and why? Which part of the lake are different species found? And how are they feeding? You’ll see some dabbling along the surface, while others are diving.
What happens if the lake totally freezes over and all the waterfowl are gone? Then it’s a good time to go back to your cozy home, have a mug of hot chocolate, and read up on these marvelous creatures. Learn some of their names so that when the freeze is over and the lake is accessible again for the waterfowl, you’ll appreciate their beauty and resilience even more.
If you want to learn more about waterfowl movements and other bird species in your area, I highly recommend getting familiar with ebird.org. It’s a fantastic tool from the Cornell Lab of Ornithology and the world’s largest biodiversity-related citizen science project.
Please let me know if this article got you out there watching birds, or what I have to do to get you interested in learning more about our avian friends. Happy Birding!
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