Sunday, May 6, 2012

Not-So-Solitary Sandpipers in Flooded Field

Saturday evening, while doing our bluebird nestbox rounds south of Northfield, we noticed that the afternoon's heavy rains had left standing water in many farm fields. Flooded fields are prime habitat for migrating shorebirds, so we were on the lookout. At one particularly wet spot I saw something small and pale, so we pulled over to take a closer look.

We saw one, and then another, and eventually as many as seven or eight medium-sized shorebirds -- not all together, but here and there in ones and occasionally twos. A red-winged blackbird flew at one and flushed it, and we noted that the two birds were of very similar body size, which gave us a useful reference point. When we got close enough to see it, a noticeable white eye-ring confirmed the identification: these were solitary sandpipers. I just checked the comparative body length of the two species, and our impression of similar size was correct: solitary sandpipers are about 8.5 inches and red-winged blackbirds are about 8.7 inches.

We have most often seen these one at a time, as their name suggests, but the Cornell Lab's All About Birds site says, "While not truly solitary, it does not migrate in large flocks the way other shorebirds do," and National Geographic Complete Birds of North America notes that they are "usually seen singly or in small groups." Wet, grassy areas are a common setting for solitary sandpipers. On May 1 last year, in fact, we saw one in a flooded low area of lawn near our house, right in Northfield.

Like most of the shorebirds we see in Minnesota, these are just passing through on their way from their winter homes, ranging from southern Mexico into much of South America, to their breeding grounds in Canada and Alaska.

I was fascinated to learn just now, as I read about these pretty shorebirds, that they actually nest in trees, in the abandoned nests of songbirds, particularly particularly those of the American robin, rusty blackbird, eastern kingbird, gray jay, and cedar waxwing. The Cornell Lab site says, "Of the world's 85 sandpiper species, only the solitary sandpiper and the green sandpiper of Eurasia routinely lay eggs in tree nests instead of on the ground." This nesting habit was not discovered until 1903, 90 years after the species was first described by ornithologist Alexander Wilson.

So here are the things about solitary sandpipers that will stick in my mind:

  • White eye-ring
  • Same size as a red-winged blackbird (the legs and bills are very different, obviously)
  • Flooded fields are likely habitat (this is true for a number of shorebird species, of course)
  • They nest in trees!

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