They are the only songbirds with the ability to dive straight into rushing water to feed on insects and not drown. They actually run and use their wings to "fly" along the bottom in search of insects and other tasty invertebrates. As their name implies, when perched on a rock of dry log above water, they do a funny little "bobbing" dance.
Dippers are robin-sized songbirds (even related to thrushes) uniquely adapted to feeding under water. Their oversized glands produce copious amounts of oil that they smear on their outer feathers, making them virtually waterproof. In addition, their plumage is unusually dense, with a greater number of outer feathers covering their heads, necks, and bodies than do most other perching birds of similar size.
No, dippers do not have gills, they hold their breath while under the surface, and have flaps to cover their nostrils and keep water out of their lungs. They have to see underwater to seize the invertebrates they feed on. To be able to do this, dippers possess highly developed muscles in the iris of the eye that allow the curvature of the lens to change, accommodating differing refractive underwater conditions.
Dippers are also equipped with very heavy "coat" of down (insulation) between the rows of outer feathers, similar to ducks and other waterfowl. The down is excellent insulation and enables the birds to maintain normal body temperatures of more than 90 F when air temperatures are as low as -40 degrees F. A nice piece of work if you live year-round in and on streams in Alaska.
The scary thing about the dipper's survival is that due to their special physical characteristics that enable them to live in cold conditions, they do not have much tolerance for heat. With summer temperatures nearing the century mark here in Central Oregon, heat can be fatal.
While the recent project of placing wood structures in the Metolius is going to improve the habitat for fish, it will also be a boon for ouzels that build their nests close to water. They are globular structures about a foot in diameter composed of an outer shell of moss and small amounts of interwoven grass and roots, with an inner, cup-like lining of dry, coarse grass.
Usually, dippers' nests are placed where water spray keeps the outer structures green and moist. The coarse inner grass resists moisture, so the inside remains relatively dry. Entrance to the nest is through a small hole, and some nests are used year after year. The nest pictured above on the end of a log in the Metolius was photographed in 1963, and it's still in use.
Dippers generally lay their eggs from April through June, but later dates have been found further north and at higher elevations. On the average, they lay four eggs, which are incubated 16 to 18 days. After hatching, the young birds spend about 24 days in the nest, about twice as long as that of birds using open nests. Dippers require more time to develop to meet the demands of their harsh aquatic environment.
"He who lives by the sword, dies by the sword," the old saying goes, and for Dippers who kill and eat aquatic invertebrates, it's sharp-shinned hawks, mink, marten, weasel, and large fish they have to be on the lookout for.
Ouzels do, in fact, have a lot going for them. Their gray plumage camouflages them as they run across boulders that line streams. Their inaccessible nesting sites, ability to dive under water, solitary habits and their habit of flattening out and remaining motionless on the surface of the water when danger approaches also make them difficult to see or catch.
Unfortunately, because of errors of past forest and stream management considerations, most streams lost nesting sites for dippers. However, today's identification and protection and rehabilitation of our Northwest streams has been beneficial to the dippers as well as the fisheries.
Aquatic habitat researchers say, "Healthy dipper populations on upland rivers throughout the world indicate healthy river ecosystems." If this premise is true, then the Metolius, Deschutes Rivers and Whychus Creek are in good shape.