Staging sandpipers signal season’s end
Feed. Rest. Repeat.
For me, autumn culminates not with the falling of the leaves, but with shore birds standing on the shore, waiting for the tide to turn and expose the mudflat buffet where they will fuel up for the next leg in their migration.
Technically, the shorebird group includes sandpipers, plovers, knots, curlews, dowitchers, phalaropes and turnstones; but not herons, gulls, or cormorants. Thirty-eight species of shorebirds spend some part of the year in Maine. Five of those are listed by the state as species of “special concern,” and one, the red knot, is federally listed as threatened. Some of the species we regularly see along the Damariscotta estuary include spotted, least, and solitary sandpipers as well as lesser and greater yellowlegs.
Their annual voyage south starts surprisingly early, often in mid-July – but then again, these birds travel thousands of miles. Many of them breed as far north as the Arctic. As they make the long journey to the Gulf Coast or Central or South America, they make stops at “staging areas,” or productive shoreline areas where they can stop over for ten to twenty days to rest and feed. Maine offers many important staging areas.
A staging area must offer two important things: a rich source of food and a safe place to roost. Shorebirds forage in the mud for small invertebrates, and they need to consume enough to be able to double their body weight. To gain the necessary fat reserves to make the nonstop, transoceanic flight to habitat in the Bahamas and southward, the birds need to make the most of every moment the mud is exposed. They gather at the water’s edge just after peak high tide, when the water is beginning to recede, and forage continuously until the tide rolls in again.
Incredibly well-camouflaged against a sand bar or mudflat edge, shorebirds generally roost on the ground in a spot near their feeding area that offers protection against predators. This might be a rocky ledge, gravel bar, or small island during high tide. Rest is critical, as the birds need to save energy for the arduous trip ahead.
Banding studies in Maine show that shorebirds exhibit high fidelity to traditional staging areas. If a foraging or roosting area is lost to development, pollution, or disturbance, the birds do not readily relocate to new areas. This in turn jeopardizes their ability to survive migration.
We may continue to see a few shorebirds still feeding in Maine through November, but then they are gone until next spring – with one special exception. The Purple Sandpiper, named for the seldom-seen purple sheen of its wing feathers, will stay the winter here in Maine. This hardy bird breeds in the artic tundra and winters, without foraging competition from other shorebirds, along the rocky shores of the North Atlantic. We do not generally think of sandpipers as being snowbirds, but the purple sandpiper is one! And I certainly hope to see some along the shores of the Damariscotta this winter.
Photo credits: Solitary sandpiper by Walt Barrows. Purple sandpiper courtesy of Fyn Kynd via Flickr.