How do birds stay warm in the winter? 

How do geese stand on ice?  How can chickadees weighing less than half of an ounce, be active at twenty degrees below freezing? Physical adaptations and behavioral strategies allow birds to endure harsh winter conditions.  

Feathers

Feathers provide efficient insulation. Birds have special soft insulating feathers called down under their outer feathers. People have used duck and goose down feathers in coats and bedding for centuries.

Eating a lot

Like the insulation in a coat, bird feathers conserve body heat. Birds have a high metabolism and must eat more in cold temperatures to produce body heat.

Migration 

If birds can find enough food, they can endure freezing temperatures. Birds migrate because their food sources are dormant or inaccessible.

Flying polar bears 

Two arctic birds of prey, snowy owls, and gyrfalcons often spend the winter on sea ice. They prey on seabirds at holes in the ice, or hunting from icebergs. Ivory gulls spend the winter scavenging at polar bear kills.  

All warm-blooded animals need insulation 

Like bird feathers, mammals have hair for insulation. Even in the tropics, mammals have hair. The exceptions are giant tropical mammals like elephants and rhinos. They can maintain their body temperatures with their mass. 

Dinosaurs have feathers

Birds are dinosaurs. Feathers likely evolved as insulation before flight.

Special blood vessels

Birds have a countercurrent heat exchange system. It allows vessels to move blood into the feet and next to the ones returning the blood to the body. Blood from the heart warms their feet.

Reducing exposure

Birds will keep one leg tucked into their belly feathers. This allows them to warm one leg and foot at a time. Birds will also tuck the exposed skin of their faces into their wings.

Shelter

Birds also stay warm by sheltering in tree cavities, under foliage, and in other crevices.

Huddling

Some bird species such as swallows huddle in groups. This allows them to share warmth and reduce surface exposure.

Fat

Large birds like geese and grouse will put on a layer of fat for the winter to store heat. Fat or blubber can comprise 30 percent of a penguin’s mass.