On the wild side—May, 2013
by Tina Mitchell
Along the rocky banks of the Arkansas River lurks a small, unique water sprite you might never have noticed—the American Dipper (right—click on the photo to see this well-camouflaged bird better). A uniquely western bird, a dipper is a stocky, slate-gray songbird, about 7.5” long and shaped rather like a fist with a stubby tail. It almost invariably can be found standing in, standing beside, or flying low over water—usually water flowing swiftly over rocks and logs. It forages by walking along the shore or among exposed rocks, sometimes with its head actually submerged, or even plunging into the water, where it may remain submerged for as long as 15 seconds. It often perches on rocks in streams, lurks beneath overhanging stream banks, and, a favorite in our area, works rocky shores beneath bridges. When out of the water, the dipper often bobs (well, “dips”) its entire body with a springy bounce.
Dippers require stretches of swiftly flowing river, stream, or creek ¼ mile to 2½ miles long. Ideally, such streams—often high in the mountains—feature lots of partially submerged boulders for perching. In winter, they require ice-free areas for foraging. Where streams remain at least somewhat ice-free all year, the birds stay on their breeding territories. Most winters, you might spot dippers along the Arkansas in our area, because the ice rarely covers extensive areas of the river. Should their waterway homes freeze, dippers in our area may move down to the Cañon City area for a few months before returning upriver to breed.
American Dippers eat nearly any insect found in the river: mayflies, caddisflies, midges, stoneflies, and craneflies, to name just a few. The dipper may walk through the flowing water with only its head submerged or it may dive, using its wings to “fly” underwater in pursuit of prey. To provide insulation from cold waters, dippers have thick coats of down and roughly twice as many contour feathers as other songbirds of comparable size. Their stubby wings are well adapted both for short flights and for use as flippers while swimming in turbulent waterways. Their strong toes and legs, along with their wings, allow them to forage efficiently in currents powerful enough to knock an unsuspecting human off his or her feet. They also walk along the streambed, probing under stones for morsels.
Dippers build their nests primarily on horizontal outcrops of rocky ledges above moving water or on structures underneath bridges. In our area, breeding season begins in late March or April. The female weaves a dome-shaped nest, about a foot in diameter, using twigs, small roots, or grasses and featuring a large entrance low on one side. She lays 4 or 5 eggs and incubates them for 13 – 17 days. Both parents share the tasks of feeding the often noisy nestlings. This next generation leaves the nest after about 18 – 25 days; nearly as soon as they fledge, they can swim and dive. At this point, the parents often divide their stream territory and their brood, with each parent feeding and tending his or her eagerly begging subgroup in different portions of their territory.
The American Dipper’s scientific name, Cinclus mexicanus, comes from “cinclus,” (Greek for a type of water bird that bobbed its tail up and down, mentioned as long ago as Aristotle). The species name, mexicanus, comes from Latin for “pertaining to Mexico,” where the nominate bird was first found. Its common name differentiates it from the Eurasian Dipper (“American”) and refers to its nearly incessant bobbing (“Dipper”) when perched along or in a stream. People have offered a variety of suggestions about the purpose of this behavior. Perhaps it helps the bird see better in a constantly changing visual backdrop of constantly moving water. Or it may be some way to communicate with other birds in a typically noisy environment. No definitive answer exists at the moment—but the behavior is probably linked somehow to better chances of survival in a lively, roaringly wet environment.
Purported to be Scottish-born naturalist John Muir’s favorite bird, he called it the “water thrush” or “ouzel” (an old name for a European blackbird). “[H]is music is that of the streams refined and spiritualized.” If you stop around bridges across the Arkansas in our area, keep an ear and eye peeled for this fascinating sprite—the only aquatic songbird in North America!—bouncing on boulders and diving into the river. You can hear see clips of a dipper dipping and “flying” under water, hear snippets of its song and call, and learn more about this species here.