The American dipper is a fascinating little bird. About the size of a sparrow and built stocky, the species catches almost all of its food while under water. Zeroing in on insects, insect larvae, and sometimes even fish eggs or tiny fish, the American dipper ducks its head under water -- sometimes as frequently as 60 times a minute -- catching prey. It will also walk along the bottom of a swiftly flowing stream, sometimes even "swimming" under the water, overturning stones and searching for its next meal.
The bird has several adaptations to help it in its role as the continent's only aquatic songbird. Beyond a sturdy build and more oily feathers than other songbirds, the dipper has an extra eyelid, or nictitating membrane, that lets it see underwater while protecting its eye. It also has scales that close over its nostrils to keep water out when it dips below the surface.
Because the American dipper requires unpolluted water to survive, it is an excellent indicator species for when an ecosystem is experiencing a downslide in quality. Some dipper populations have declined or disappeared entirely where streams have been polluted. This unique and charismatic species is yet another reason to take special care of our waterways.