Why Don’t Birds Freeze in the Winter?
I live in the North, and it’s pretty darn cold outside right now. But I see the birds sitting on the wires and flying around, and they don’t even look cold! Why don’t birds freeze in the winter?
I mean, they don’t have thick coats like dogs and bears. They have these spindly little legs that are exposed to the elements. And their nests seem like they provide no protection at all from the elements. So why don’t they freeze?
What Mechanisms Do Birds Use to Not Freeze?
Well, those thin little feathers don’t look like they offer much protection from the cold, but it turns out, they really do.
Birds puff up their feathers when they’re cold, which traps air between their body and the outer layer of the feathers. Their body heat warms this layer of trapped air, and it acts as a pretty efficient insulation against the cold.
It seems like birds are just covered with regular feathers, but if you look closely, you’ll see that a bird has many types of feathers nestled together. Check out this picture from Encyclopedia Britannica:
The three main types of feathers are the filoplumes, body contour feathers, and the interior down feathers, which are great for insulation. But you already know that if you own a down blanket or a down-filled coat.
So, all those different feathers work together to form a nice, tight layer to protect the little guys against the cold.
Why Doesn’t All That Rain and Snow Make Them Wet and Cold?
You and I both know that the only thing worse than being cold is being wet and cold. Birds sit outside when it’s raining, sleeting, or snowing, so why don’t they get sick or freeze with all that moisture?
Most birds have a gland on the upper side of their tail called the uropygial gland. It secretes a sebaceous oil. The birds use their beaks to get the oil and distribute it evenly over their feathers.
The oil has some great protective properties. It helps make the bird waterproof (although there are some people who don’t agree with that). It also has anti-microbial and anti-fungal properties. It acts as a deodorant, too. It might also have pheromones in it, which is useful for attracting mates. Some birds (like ones who clean themselves taking dust baths) don’t have this oil gland, but most do.
Here’s what the uropygial gland looks like on a parakeet baby:
Image Source: Wikimedia Commons
Furthermore, that network of interlocking feathers does a pretty good job of keeping moisture off the bird’s body, too.
Another factor keeping them warm in the winter is that birds will fatten themselves up during summer, so they have extra fat to keep them warm in the winter.
Another way birds keep warm is to flock together. Not all birds do this, but some do. Bluebirds and wrens are a couple who will gather together in a small area at night and share body heat to keep each other warm.
What About Bird’s Legs and Feet?
I sure wouldn’t want to stand outside in 0-degree weather without something covering my feet. Birds have such spindly, little legs and tiny feet with no weather protection, so how do they survive?
One method they use is to alternate their feet. They’ll stand on one leg and keep the other one tucked into that warm layer of air near their body. Then they’ll alternate and use the other leg.
Some birds have an interesting circulatory system that helps them keep their feet warm. Have you ever seen ducks sitting in cold water in the winter?
To keep their legs warm, the veins and arteries in their legs are very close to each other. So, when the warmed blood leaves the heart to travel down to the feet, it warms up the cold blood coming from the feet on its way to the heart. So, basically, they use this unique heat-transfer system.
So next time you venture out in the winter and feel terrible for those poor little birds because “they must be freezing!”, don’t worry. They’ve got it covered!