Spending most of their time on the water, it’s important that ducks stay afloat. Luckily, they’ve evolved several features that make them buoyant.
Most birds have hollow bones to keep them light enough to fly. Conveniently, this light but strong frame makes it much easier for ducks to bob on the surface of ponds, lakes and oceans.
The uropygial gland at the base of the tail produces an oily secretion that the duck spreads through its feathers with its bill. The oil gives the feathers a water-resistant coating so they don’t absorb water and weigh the duck down. Tiny barbs on each feather act like Velcro so they can latch onto each other, trapping pockets of air.
Feathers aren’t the only way ducks trap air; air sacs inside the body can be inflated like balloons so the birds are able to store air without having to hold their breath. Ducks can release the air in the sacs and the bubbles between their feathers if they want to put their heads underwater or dive for food.
Main image: James Petts/flickr