Arctic-nesting shorebird passes by on its way to Argentina
From a still and benign assemblage of cluttered stones, plants, and grass, a pale form moves haltingly. Soon it becomes apparent to the onlooker that this is some sort of animal. Details fill in, a head with a short black beak and black eyes, somewhat longish yellowed legs, it's an overall tan-colored critter with blacker flecks of feathering along its back. It's a bird alright, a buff-breasted sandpiper (Tryngites subruficollis) to be specific, but where it was a few moments before its movement gave away its position, is puzzling.
The answer, of course, is simple. With the gift of camouflage, "buffies," as they are affectionately referred to by birders, live out their lives on exposed flats of tundra, dry beaches, and short prairies with just the right cryptic feathering, an adaptive biological response to help thwart predators. Still, the birds are known to be very tame, allow a close approach, and usually walk away from danger in lieu of flying.
Making buffies so sought after by birdwatchers is the fact there just never seems to be very many of them. They are reported every year around here but usually only in small groups. I think the biggest flock I've ever seen consisted of maybe 70 birds, a pretty rare exception. The entire world population is thought to be in the few thousands although there was likely many more decades ago, before market hunting decimated populations of this tame bird in the late 1800s. A curious trait it exhibits likely added to its precipitous population decline: When a flock member is wounded, the rest have a tendency to return to it.
The species causes a stir outside a very narrow migratory corridor down the middle of the continent. Birds of North America Online notes buffies are, "virtually unseen on Atlantic or Pacific Coasts during the spring," although the fall path is much broader. Adults leave the nesting grounds and show up locally about the end of July, well prior to juveniles. Weeks later, all sightings are of juvenile birds, which is all we are seeing anymore this fall.
Buffies nest in the high arctic in summer while wintering in the Pampas region of South America, mainly Argentina, crossing the Gulf of Mexico enroute. The birds are thought to be night migrants although no one is certain.
I find the species name--subruficollis--somewhat misleading. Subrufus would be a Latin word meaning dull red; collis means simply neck, or collar. I have never seen any red on these birds nor has anyone with whom I have spoken. Instead, the bird's background color is a rich, tawny ochre not unlike finely tanned leather. Nowhere is there any red.
As mentioned, a buffy's back is adorned with black-centered feathers, both juveniles and adults. Juvies, however, display a rounder black portion to their feathers with wider whitish edging, giving them what nearly all field guides say is a "scaly appearance."
Apart from their rather singular appearance, perhaps the coolest characteristic of buffies is their mating system which is unique among all the shorebirds. In a fashion similar to our prairie grouses, males employ a lek system and defend small territories within it by displaying poses an observer might describe as a fan-dance. Unfortunately it is rarely seen away from high arctic breeding grounds. One expert briefly explains the male's performance art as having "his belly puffed out like a big pear with his white wing linings held up in front of his face."
One really cannot mistake buff-breasted sandpipers for any other shorebird, they being so different. Look for round-headed pale birds the color of buckskin horses anywhere you normally find killdeers. This includes freshly hayed fields, grazed pasture, even expansive mowed areas such as West Fargo's Rendezvous Park. The birds will be rather tamely walking around and looking--as Pete Dunne describes--"gentle, baleful." Even knowing this they are not always easy to see. But when all the other birds have flushed, if you are lucky the remainders will be buff-breasted sandpipers.