- Written by Clyde McMillan-Gamber Clyde McMillan-Gamber
Up to six kinds of small birds nest or winter along flowing streams in North America.
And all these birds have at least three characteristics in common: feathering that camouflages them, a diet consisting of a variety of invertebrates, and their constantly bobbing or dipping some part of their body when walking along waterways to get food.
For a long time I wondered why these little birds were always dancing as they walked along the edges of waterways.
Then, one day, I noticed some twigs bouncing vigorously in a brook’s current near a spotted sandpiper that was bobbing its tail up and down with the same rhythm as the twigs in the running water.
Could all that dancing along small waterways be a form of camouflage among birds of different families?
If so, that streamside habitat shaped those unrelated birds into doing a similar activity to escape the attention of predators. All those kinds of birds developed a trait that converged them into that niche to survive in it.
Perhaps, too, that rhythmic, comical dancing is a form of communicating among birds of a species under the guise of small bits of wood bobbing along in a tumbling brook or stream. The birds get their messages out without making themselves vulnerable to predators.
The bobbing and dipping of these various types of unrelated birds to a quick beat is entertaining to watch. And that humorous activity helps in identifying each species.
Gray-feathered dippers raise two or three young per brood in crevices in streambanks along cascading, small waterways in the Rocky Mountains of the United States and Canada. Dippers bounce their whole bodies up and down as they walk. And they walk on the bottoms of waterways to get invertebrates as well.
Spotted sandpipers raise four young in a brood along streams over much of North America. They bob their tails up and down constantly as they walk along little waterways in meadows.
Louisiana waterthrushes are a kind of warbler, most of which are woodland nesting birds. Waterthrushes rear offspring in dead-leaf-lined crevices in streambanks along streams in woods in the eastern United States.
And they continually pump their tails up and down, much like spotted sandpipers, as they walk along woodland streams to snare invertebrates.
American pipits are sparrow-sized birds that nest on the Arctic tundra but winter in open habitats, including bare fields in farmland across much of the United States.
But when snow covers seeds and invertebrates in fields, pipits gather along small waterways in pastures to look for invertebrates to eat. These little birds bob their tails as they poke about shallow water for food.
Winter wrens are 4 inches long and warm brown, and they scurry along small waterways in woods like feathered mice.
They hunt invertebrates among exposed tree roots, fallen logs, carpets of dead leaves, and stones along waters’ edges, dipping and dancing their whole bodies as they move along. Each winter wren shelters during winter nights among tree roots and fallen logs along the same brooks where it hunted food.
Rusty-capped and yellow-bellied, the lovely palm warblers nest on the ground in woodland bogs in northern North America. And they wag their tails as they walk over the ground and along little waterways in the woods in search of invertebrates.
Being camouflaged, all these birds are tough to spot but fascinating to experience when they are found. But even if they are not spotted, it’s interesting to note their presence and their comical ways of avoiding capture by predators.
There seems to be no end to ways in which life strives to survive. Nature is always intriguing, all the time.
Clyde McMillan-Gamber is a retired Lancaster County Parks naturalist.