Photo: Fluffy bird

Photo by Elsa Bouman

Birds’ feathers provide remarkable insulation against the cold, and the oil that coats feathers also provides waterproofing, which is important since the only thing worse than being cold, is being cold and wet.

And just like the coats people wear, birds tend to get puffier in winter.

A bird’s body heat warms the air between its feathers, so birds fluff up in the cold to trap as much air in their feathers as possible.

The more trapped air, the warmer the bird.

--Elsa Bouman