Mon, 08/27/2018 - 12:30

Kristen Lindquist

(Photo courtesy Keith Carver)

While walking the grounds of Plants Unlimited one recent August day, I was surprised to turn a corner and flush a shorebird. Somewhere near the hydrangeas, I came upon it again: a Least Sandpiper. I realized with a shock that despite us humans feeling like we were still in full summer mode here on the Maine coast, shorebirds had already begun, once again, their southward migration.

The summer nesting season in the Arctic, where most shorebirds nest, is shorter and more intense than ours here in the lower latitudes. Unbeknownst to most of us, some sandpipers began to leave their tundra breeding grounds as early as June and July, before most of our tourists had even arrived yet. These early migrants were primarily adult birds. They may have failed to hook up with a mate or experienced nesting failure with not enough time left to try again. Or, with several species of sandpiper only one parent lingers with the young after they have hatched out; the other (often the mother bird) heads out early to score a good spot on the wintering grounds. A head start comes in handy when you're potentially flying all the way to South America.

By August, the first big waves of juvenile shorebirds arrive. The Least Sandpiper I saw had the bright, fresh, copper penny plumage of a newly minted bird, indicating that it was a juvenile on its maiden migration flight. (Non-breeding adult plumage is generally a worn grey-brown.) It's amazing to think about: this little bird, barely larger than a chickadee, emerged from an egg just weeks before, and now, without any parental guidance, has embarked on a flight of thousands of miles to a place it has never seen before! Migration is truly an everyday miracle.

Fortunately, this young bird is not alone. (In fact, I saw two others of this smallest of sandpipers hanging out at Plants Unlimited that day.) Numbers of southbound migrants burgeon throughout August. Least Sandpipers and other small sandpiper species, collectively referred to as peeps, shift through saltmarshes and tidal flats by the hundreds in shimmering avian clouds.

Hearing the sweet cacophony of the shorebirds' shrill calls for the first time each August at Weskeag Marsh in South Thomaston is a bittersweet moment. The poignant sound conjures for me a strong sensory image of the tangy, pungent scent of the saltmarsh, the hum of crickets in sere grasses, and that particular rich quality of light of late summer. But it also conveys a sense of urgency warning of the relentless passage of time. The birds are leaving, headed south. Our brief, glorious Maine summer is winding down, this time of warmth and abundance will soon pass.

Clouds of restless birds contribute to this transitory mood, as they move back and forth in the salt pannes, feeding continuously, dodging birds of prey. At the appearance of a falcon, the whole flock twists and turns as one aerial being, then eventually settles back down to feed. The peeps leave tracks like tiny hieroglyphics etched into the algae-covered marsh mud. Deciphered, they'd tell an ancient story.

Migrating sandpipers feed with great intensity, ever watchful but ever probing as they fatten up for the next leg of their flight to Central or South America. Given the distances these birds need to fly, stuffing themselves is a life-or-death situation. When the Nature Conservancy first tracked a whimbrel (a larger sandpiper) during her spring migration, they were shocked to learn that she flew from the Virginia coast all the way to northern Alaska in six days, non-stop. When they'd attached the the tiny transmitter to her back, the biologists had described her as a “chicken whimbrel" because she was so fat. Once they realized what she had done, it became obvious why she had been so beefed up.

If caught on Weskeag Marsh, a Least Sandpiper would sport a similar layer of fat relative to its body weight, to help fuel its continuing journey to at least as far as the southern United States, if not northern South America. Least Sandpipers feed on a variety of little invertebrates, including snails, slugs, tiny crustaceans, flies, beetles, and other bugs, and even some marsh plants. The miracle of migration grows even more amazing when you consider the millions of tiny bits of food hauled up from the mud and brine that are making it possible.

Plump, fueled-up Least Sandpipers and other shorebirds were over-hunted by market hunters prior to the enactment of the Migratory Bird Treaty Act in 1918. While the Act, which prohibited the killing of migratory bird species, came too late to save such shorebirds as the now-extinct Eskimo Curlew, Least Sandpiper populations rebounded. In recent decades, however, numbers of this widespread bird have declined due to habitat degradation along its migration route. For birds flying thousands of miles, those saltmarsh and mudflat pit stops along the way are vital. Weskeag Marsh is a crucial stopping-over point.

With their grey-brown coloring, Least Sandpipers and their shorebird cousins blend in well with the dry grasses and sedges of the marsh. They're most visible when feeding in the shallow pools or open flats, or in flight, when their pale undersides flash in the sunlight.

Driving by Weskeag, you might look out over the late summer salt marsh and see few signs of animal life. But at ground level, the marsh brims over with activity as flocks feed frantically all around you or fly back and forth overhead—and it's easy to get caught up in the birds' restless energy. This is summer's last hurrah, the feast before the flight. Soak up this surge of vitality, this sunlight, while you can. The birds are moving on soon, and winter is coming.

Note: All photos accompanying this piece—which feature individual Least Sandpipers and flocks of "peeps" in flight at Weskeag Marsh—are used with permission from Keith Carver (https://krcarver.zenfolio.com/).

Kristen Lindquist is an amateur naturalist and published poet who lives in her hometown of Camden.