Flight Lines: Shadowy shorebird remains an enigma
Sticks to himself, doesn't play well with others, quiet, a loner. This could very well appear in the report card of a young school child with problems in need of addressing. It could also describe one of our common, but seldom noticed shorebirds, the solitary sandpiper (Tringa solitaria).
I've been looking at birds for over 30 years now, yet cannot recall ever seeing more than one solitary sandpiper at a time. Most shorebirds are keen on maintaining large groups, sometimes in the thousands. Not this one. A more apt common name could not have been given it.
It's a medium-sized bird slightly smaller than our common killdeer. A dark, olive-brown back speckled with white spots blends extremely well with the dark, shadowy areas it typically inhabits. The bird's throat and belly are white but is separated by a heavily and darkly-streaked breast. Its legs are greenish yellow which helps to separate it from similar looking birds. Especially when alarmed, the bird habitually bobs it head.
Solitary sandpipers can be confused with a much more common shorebird which nests locally and even occupies similar habitats - the spotted sandpiper. But spotted sandpipers bob their tails constantly and lack the back-spotting of the solitary sandpiper. Plus it has a white eyestripe, a feature the solitary lacks. Lesser yellowlegs is another species common in migration which may confound the casual observer. But its bright yellow legs and white tail should be enough to discount a solitary.
There exists a sister to this bird though, the green sandpiper. We don't have to worry about running into it here since it's an Eastern Hemisphere bird, but the two are so closely related they were once considered the same species.
Setting this particular species apart from other shorebirds is a rather odd characteristic. It mostly shuns the wide open beaches and mud flats favored by virtually every other shorebird. Instead, solitary sandpipers usually forage along wooded streams or small ponds. A common place to find them in spring is along the muddy banks of our local rivers or even in ditches. Alone of course.
It doesn't stop here to breed. Instead the birds head farther north into Canada and Alaska (it has rarely nested in Cook Co., Minn.), where it finds muskeg ponds in the boreal forests more to its liking. Because of the remote and inaccessible nature of their nesting grounds, very little is known of this curious shorebird. Again, the fact it also migrates alone or in tiny flocks adds an additional dark hole in our understanding of it. Sources I referred to were filled with phrases like "no information," "unclear," and "no data." A span of 90 years elapsed between the time the solitary sandpiper was first described by science and the first nest was found.
What little we do know of its nesting habits offers up yet another interesting nugget. Of the shorebirds breeding in North America, it's the only species to regularly lay its eggs in tree nests. Not only that but solitary sandpipers do not construct nests themselves. Rather, the birds reuse the abandoned nests of songbirds. Other species' nests recorded being used by solitary sandpipers includes American robin, rusty blackbird, gray jay, and cedar waxwing; all typical boreal nesting birds. There are likely more but not enough is known about them to expand the list.
After nesting, this shorebird heads south to winter in almost all of South America north to southern Mexico and some Caribbean islands, where it forages in similar wooded habitats.
Solitary sandpiper populations are not considered to be threatened but no one really knows for sure. There remains a vast unexplored gray area for some young enterprising biologist to make a name for herself. Your resume should probably include phrases like, "performs well in mosquito-infested habitats," "undaunted by impenetrable terrain," and "technical consultant for the TV show, 'Survivor.'" Or you could simply wait for fall, see the birds in migration, and wonder about them like the rest of us.