As the colder weather approaches, birds of all shapes and sizes have to start adapting to the colder weather. Extra winter feathers, shivering, and roosting with others are just a few of the ways they are able to keep cozy throughout the cold weather months.
Many birds grow extra feathers as part of a late fall molt in preparation for winter. These extra feathers provide birds with the perfect insulation to stay warm. Additionally, birds have a unique adaptation called the uropygial gland. This special gland releases oil that coats their feathers, ultimately making them waterproof and providing even more insulation. Sometimes you’ll see a bird “fluffing” its feathers. When this happens, they are creating air pockets that serve as a heat source.
Have you ever walked past a group of one-legged geese and wondered what they are doing? Well, it’s simply to keep in body heat. Waterfowl in particular circulate blood through their feet using countercurrent heat exchange. Warm blood flows to their feet and back into the body and in the veins. As the veins take in heat, the artery’s internal temperature decreases. Thus, the temperature in their feet adapts to the temperature outside and reduces heat overall. Since there is a small temperature difference between the ice and their feet, this process becomes efficient for waterfowl as they lose minimal body heat overall. You can typically see birds lifting one leg into their feathers which are done to conserve body heat. Another thing this animal does to stay warm is tucking its bill underneath its feathers. By doing this, they draw in warm air.
Similar to people, birds shiver as well. Due to birds’ high metabolic rate, they have to burn a large amount of energy just to stay warm. When they shiver, their metabolic rate goes up and so does their body heat. Shivers are just a short-term solution as it does require the burning of lots of calories and isn’t very efficient.
During the winter months, a bird party comes in handy. Cuddling with one another is the perfect way to generate body heat, using minimal energy. Cavity nesters such as nuthatches will huddle in tree cavities and generate body warmth inside. Tree cavities are ideal as they protect the birds from the cold weather as well as any predators that might be around.