American dipper is unique among songbirds

Of the Minnesota records that I've been able to uncover through quick Internet searches, verified, documented observations of this unusual bird have been recorded along the North Shore within the fast flowing, cold water streams and rivers flowing into Lake Superior.

Of all places in Minnesota — what with the area's mountain-like landscape and clear running rocky streams — the American dipper would find itself much at home, albeit hundreds of miles east of its normal and preferred range and associated breeding and nesting habitats.

Last October I received an email from retired biologist Mary Jane Gall of Woodbury, Minn., who reported observing a single dipper in her yard while she was doing some lawn-care work. She told me that the bird allowed her to get quite close, too, as the bird seemed to be foraging in a pile of day lilies that she had just recently cut down. Lucky her!

Indeed, there's no other bird quite like the extraordinary American dipper. In fact, this species of dipper is the only dipper in all of North America.

Other species, which include four other dippers, inhabit South America, Europe, and Asia. The range of the American dipper includes Alaska and southward through the western continental United States, and south to the mountains of Panama.

American dippers are squat birds with rather long legs for their size. To compare with other common birds, the dipper looks like a gray catbird without much of a tail. Likewise, and because of its short tail, American dippers also resemble wrens.

Not very colorful, (overall dark gray with slightly brownish heads) both sexes are identical in appearance. They also have white eyelids that can be observed when the birds blink, appearing almost "flashy" when they do so. But what they perhaps lack in visual beauty is more than made up for by the birds' charisma. No other songbird behaves quite like the American dipper does.

As its charming namesake seems to suggest, American dippers not only submerge themselves underwater when hunting for food, they also constantly "dip", or bob, their bodies up and down as they perch on rocks along their fast-flowing riverine habitats. American dippers are also the only songbird that regularly swims on the surface of the water — their unusually oily feathers are no doubt some of the reason for this amazing ability.

The diving dipper is so suited to its environment, so specialized, that the bird finds itself residing virtually competition-free. Few other birds exploit underwater resources like the American dipper. The astonishing bird is visible one moment bobbing up and down atop river rock, while the next moment it has disappeared into the water; only to resurface on or nearby the same rock a moment later.

Searching for aquatic invertebrates like larvae that hide and crawl on stream bottoms as well as other aquatic organisms such as tadpoles and small fish, including fish eggs, American dippers are experts at finding and capturing these prey items in the fast moving waters of mountain streams. They even have the ability to "fly" underwater, using their wings to aid in propulsion, maneuvering, and stabilization in swift flowages.

One of the interesting aspects of dipper behavior has to do with the belief that the birds communicate with one another, in part, through their bobbing and blinking actions. As anyone can attest, streams and rivers are often noisy environments complete with cascading waterfalls and turbulent water coursing over and around rocks and woody debris.

Though dippers are vocal birds that sing high-pitched whistles and trills, in addition to emitting high and buzzy call-notes, their aural ability in such environments is frequently compromised. Thus, visual displays are important to dippers that are intent on communicating and keeping track of one another.

Regarding physical attributes for their watery world, American dippers also possess two interesting features that better equips them for underwater foraging. In order to see well, dippers have nictitating, transparent membranes that cover their eyes while underwater. Moreover, dippers have movable nasal flaps of skin that close shut so water cannot enter their nasal passages.

Also interesting, and rare among songbirds, is that dippers molt both their wing and tail feathers all at once, becoming flightless for a period of time just like ducks and geese do.

I hope to observe the delightful American dipper for myself in its natural habitat someday. I know I could spend countless mesmerized moments watching the dipper bobbing its body and diving and swimming for its food. And while the species does show up from time to time along fast moving streams of the North Shore, our best opportunities to observe this fascinating water songbird will occur much further west as we get out and enjoy the great outdoors.