Bird Watcher's General Store

Duck Feet Do Not Freeze
12/10/10


Dear Bird Folks,

As I watch the ducks swimming out in Pleasant Bay I’m wondering why their little, thin feet don’t freeze. After only being out in the cold for a short period my toes are turning blue, yet the ducks glide past me with happy, smiling faces. How can they stand such cold?

– Julia, Orleans, MA

Close, Julia,

As I read your note the line about ducks with “happy, smiling faces” stuck in my head. Then I had a great idea. The Smiling Duck Café would be the perfect name for a coffee shop. It would have duck pictures on the wall, duck coffee mugs and anyone named Donald or Daffy would get free coffee. Soon there would be a Smiling Duck Café on every street corner and Starbucks would be forced to change their name to “Starducks” if they wanted to compete. I was just about to pick up the phone and ask you to be my new business partner when a quick Internet search revealed that there already is a Smiling Duck Café in Carlisle, MA. (Carlisle?) Nuts!! Oh, well. Maybe it wasn’t such a good idea. I drink way too much coffee already and your blue toes would have freaked out the customers. Hey, perhaps we should open the Blue Toe Café instead. I’ll get back to you.

When you think about a bird’s ability to survive a New England winter it’s mind-boggling. It really is. Birds are outside in the coldest weather and they never get to go inside to warm up, not even for a minute. They don’t get to sit beside a crackling fire, wrap up in a Snuggie and drink hot toddies. However, most birds can find a sheltered spot for the night. Some crawl into tree cavities while others hunker down in dense thickets to get away from the biting wind. Ducks aren’t so lucky. They are out there, totally exposed to the worst weather, 24/7, and the best they can do for protection is tuck their bills into their feathers. And if all that wasn’t bad enough, they have to spend the entire winter sitting in icy water. Could it get any worse? I’m such a wimp that if the sleeves of my Snuggie get wet when I brush my teeth, I have to put on a new one or I’m freezing for the rest of the night. (It’s always good to have a closet full of Snuggies.)

While ducks may not have access to the same things that keep us humans warm, they do have something even better. They have down. With all of our technology and advancements, we still haven’t been able to produce anything that insulates as well as duck down. Down feathers are the fluffy feathers that are found underneath a duck’s tough outer feathers. The little pockets of air in the down not only trap the bird’s body heat, but the trapped air also helps keep the bird buoyant, allowing it to float effortlessly on the water.

Unfortunately for the ducks, they don’t have any down on their legs and feet. As a result, they have to spend the entire winter totally barefoot. To offset the lack of having warm shoes or even leg warmers left over from the 80s, ducks have evolved a less fashionable option. The blood moving to and from their feet circulates in what biologists call a “countercurrent.” (FYI: Countercurrent should not be confused with “counterculture.” Countercurrent has to do with blood flow; counterculture is what you find in places like the Blue Toe Café.)

If we are outside in the cold for too long, our bodies slowly restrict blood flow to our extremities. The reason for this restriction is to keep the body’s core temperature from dropping, which helps prevent hypothermia. That’s a good thing. But there is a down side. With no blood flowing to our feet and hands, we become susceptible to frostbite. That’s not so good. To avoid getting frostbite, we go inside to warm up; but wild ducks don’t have that option. Instead, they have a system of heat exchange, or countercurrent, in which the veins and arteries wrap around each other. As the blood flows from a duck’s heart, it warms the cold blood returning from the feet. This procedure moderates the incoming blood and keeps the duck’s core from becoming chilled and hypothermic. Who knew ducks were so complicated?

The other reason ducks can run around barefoot was mentioned in your question. They have, as you said, “thin, little feet.” Their feet are thin because they contain few muscles or soft tissue. Long tendons control their feet while most of their muscles are higher up in the legs, kept nice and warm by feathers. All of this means very little blood is needed to keep the feet functioning. It is estimated that as little as 5% of a duck’s body heat is lost through its feet. And don’t forget that ducks have the ability to withdraw their feet and keep one or both tucked in their feathers, thus further cutting their heat loss.

I’m not saying winter is easy for ducks, it certainly isn’t. But they’ve been doing it for a long time and have evolved some very effective survival strategies. If you’re still worried about your ducks, Julia, you could invite them in for a cup of coffee, hot chocolate, or even a hot toddy. Just don’t offer them a glass of Cold Duck. That would be wrong on so many levels.




Artwork by Catherine Clark


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