For loons, daily preening is necessary in order to maintain the waterproofing of their feathers and keep them aligned. Individual feathers are like shingles on a roof—their interlocking structure creates a barrier so that water cannot reach the skin. Loons and other birds secrete oil from a gland at the base of the tail called the uropygial gland. When preening, loons take oil from this gland in their bills and use it to coat their feathers.
Because preening loons appear to be picking at their bodies, they are often mistaken for tangled or injured loons. A preening loon may:
- Roll onto its side or back and pull at its breast and belly feathers with its bill
- Stick one leg in the air and paddle in circles
- Rub its head against its back and shoulders to disperse oil
- Flap its wings hard and rise out of the water, appearing to be unable to take off
- Shake its wings, head, and tail