Penguins carry a layer of fat under the skin that helps keep them warm.

The longer version

Blubber is a thick layer of fat under the skin, and fat conducts heat far less readily than muscle or blood, so it slows the outward flow of body heat. It also works as a fuel store, which matters for a bird that may fast for weeks while incubating or moulting on land.

Penguins pair it with dense waterproof feathers and with countercurrent heat exchange in the flippers and legs, where outgoing warmth is handed back to the returning blood instead of leaking away at the surface. Cold water draws heat out many times faster than air at the same temperature, so the insulation has to be thorough.

Where this entry sits

Here you will find feathered trivia about flight, migration, nests, eggs, and the songs birds sing. Expect short surprising facts on penguins, owls, hummingbirds, and other familiar birds from gardens, forests, wetlands, and distant coastlines. The full list sits on the Birds page, where every entry is listed in order.