“Here I find the little water ouzel as much at home as any linnet in a leafy grove, seeming to take the greater delight the more boisterous the stream. The dizzy precipices, the swift dashing energy displayed, and the thunder tones of the sheer falls are awe inspiring, but there is nothing awful about this little bird.”
-John Muir, My First Summer in the Sierra (1911)
The American dipper (Cinclus mexicanus) is a dryad of the rapids, the nictitating nymph of our salmon’s natal streams and the only truly aquatic songbird of the Pacific Northwest. Also known as the water ouzel (from the Old English ōsle, meaning “blackbird or thrush”, though dippers aren’t thrushes), dippers are small and wren-shaped, with dainty gray legs, a stout, rounded body, and stubby upturned tail. Almost entirely slate-gray, they have curiously white eyebrows that flash as they blink. (Or are they winking?) Dippers inhabit montane freshets and rivers with clear, turbulent water—their west-inclined range stretches from Alaska to Panama—and if they are seen to migrate at all, it is during winter, when they move downstream, down the mountain, away from the eddy-trapping ice.
Dippers are so named for their characteristic bobbing behavior, which seems to occupy the birds at every waking moment outside of flying, brooding, and diving for food. A dipper does not stand pensively at streamside, or hold stoic, stolid vigil over the riverine; a dipper dips, all day, every day. Their compulsive half-squats—which, unlike in wagtails and pipits and other tail-twitchers, employs the entire body—may be a form of visual communication between the largely solitary, territorial birds, or it might be something else entirely. I personally prefer to think they are simply keeping their muscles spry, much like the sprinter who runs in place or drops into a quick set of lunges before the race.
Like any self-respecting water bird, dippers sport a number of adaptations specially designed for the life aquatic. Moveable scales cover the nostrils while submerged, and a third eyelid called the nictitating membrane acts as a pair of goggles, allowing the birds to use their eyes to track the insect and fish larvae that constitute their prey. Dippers are diver-adepts, flapping their wings to “fly” underwater at thirty-second intervals and sometimes plunging straight to the bottom, where they grip the substrate with their toes and walk along the riverbed, the current at their backs. Because mountain streams are invariably cold, dippers insulate with unusually dense plumage, and their hemoglobin-rich blood grants them the greatest oxygen-carrying capacity of any passerine. Dippers preen their feathers with water-proofing oil like many other birds, but their preening glands are ten times larger than those of similarly-sized species.
Both sexes sing—a series of high whistles and piping trills, at a frequency above the river’s din—possibly to defend territory or possibly for the sheer pleasure of it. Dippers live singly until mating season in the spring, when a nest is constructed near water and two to five white eggs are laid and incubated by the female. This nest is volleyball-sized and hidden from view—sometimes behind a waterfall, or atop a boulder, or in the nook of an overhanging tree—and it is often made of living moss, watered by the river’s spray.
The dipper’s preference for limpid, well-oxygenated streams overlaps that of the salmon, and it is common to find the two creatures cohabiting prime riparian areas. As the dipper is a more or less permanent streamside resident—and a relatively picky one at that—its presence often indicates a healthy ecosystem, high in water quality and low in pollutants. Where there are dippers, there are likely to be salmon, and vice versa; a dip in one population doesn’t bode well for the other.
To conclude, here again is Muir, all dippy with the dippers:
“What a romantic life this little bird leads on the most beautiful portions of the streams, in a genial climate with shade and cool water and spray to temper the summer heat. No wonder it is a fine singer, considering the stream songs it hears day and night. Every breath the little poet draws is part of a song, for all the air about the rapids and falls is beaten into music, and its first lessons must begin before it is born by the thrilling and quivering of the eggs in unison with the tones of the falls.”