You’ll have to take our word for it when we say that it was a lot colder outside when we decided to dust off this piece from February 2015 for a rerun. But since winter is about to make a comeback, it remains appropriate, we think!
How DO birds keep from freezing in freezing temperatures on land and in the water? Our nature writer, Marjorie Rachlin, has the answers.
Have you noticed the mallard ducks swimming lazily in Rock Creek when it’s cold and there is snow on the ground?
“Why aren’t they freezing?” a friend asked.
I went to the web to find out. It turns out that birds have several different kinds of feathers that keep them warm. When we look at a bird, what we see is the outer contact feathers. They are the first layer of defense, providing insulation and waterproofing. But beneath them are an even more important set of short, fluffy feathers called down, much like our quilt stuffing.
A contact feather has a firm, flat construction, its branches tightly locked like Velcro, to make it waterproof. Contact feathers grow closely together so they can provide insulation and the structure needed for flight.
Beneath them are the down feathers, which are fluffy and loose. They trap warm air from the bird’s body and keep it from escaping.
In cold weather, birds puff up their down feathers to retain heat. You may have noticed that some birds in your yard look bigger and fatter when it’s cold. Some birds, like eiders, can endure in temperatures as low as 30 degrees below zero.
Feathers are important year-round, and birds spend a lot of time preening – fluffing their feathers and combing them with their bills. They also oil them, using a waxy oil from a gland usually located at the base of the tail.
Why is that bird standing on the ice?
When I drive down Rock Creek Parkway I often see a group of gulls near the Kennedy Center, standing on the ice on the shore of the river. “Aren’t their feet freezing?” I ask myself.
Some of them are one-legged wonders, standing with the other leg tucked up against its body for warmth, but that’s only part of the story. Birds have developed a complicated system to preserve heat loss from the arteries and veins in their legs and feet, and this allows our gulls (and our mallards) to keep the temperature in their extremities low, but warm enough. See AskaNaturalist.com for more details on why their feet don’t freeze.
How do backyard birds cope?
Our common “feeder” birds have developed a number of strategies to survive the cold. Food is basic, and you may notice that they often arrive at the feeder in flocks, many types at once. The reason for this is that many eyes help spot predators, and we have several kinds of local hawks (Cooper’s, red-tailed, red-shouldered) that find our feeders the perfect restaurant. (Read more about table manners at the bird feeder.)
The seed-eaters – sparrows, doves, cardinals – are getting well-fed at Forest Hills feeders. Others, like the woodpeckers and the Carolina wren, need fat, and they prefer our suet. Carolina wrens can’t take prolonged temperatures below 10 degrees – they are really a more southern bird – but luckily DC seldom has such weather.
All these birds use their down feathers, and they make it a point to keep out of the wind, even staying on the other side of a tree trunk. For a roost, they look for a tree cavity, a hole in the eaves, a thick bush or evergreen, or even a bird house, where they will be warmer.
Where have all the robins gone?
“I haven’t seen any robins lately,” people say to me, and I’ve been missing them too. In the summer robins pair up, and a pair or two may be in your yard every day. But in the winter, robins gather in flocks to search for food, and the flock may go away for several weeks before you are surprised by a sudden return. You won’t see many robins when it snows – a study by the Cornell Lab of Ornithology has found they don’t like the least bit of snow cover, probably because it interferes with their preferred feeding method.
Recently I went up to Rock Creek Park on a day when the sun was out and the temperature was around 45 degrees. There, on a grassy lawn near Military Road, were ten or so robins. They were doing their feeding behavior: Hop, hop, hop, pause… listen, maybe peck – and repeat. I couldn’t tell whether they were getting any worms, but I can see why the books tell us they don’t like snow.
The mallards are courting
In late fall, the mallards start a long courtship to form new pairs. The males show off, but the female makes the decision. You can watch this behavior now in Rock Creek – often they are seen in the stretch of water between Peirce Mill and the Broad Branch turn off.
You may see a male and female facing each other and bobbing their heads. Or a male pulling his wings and tail up in a way that shows off the blue patches on his wings. Sometimes a male will raise his head and breast out of the water and give a little whistle.
This video, from the Cornell Lab of Ornithology, shows some interesting courting behavior by mallards and other ducks.
In late March these mallards will build nests near the creek or up on one of the tributaries like Soapstone Creek, and we may see ducklings by early May. So hang in there! Spring will come.