It’s August on Nantucket, and as the tide falls, the emerging flats are filled with shorebirds of every type, both large and small. But even among other long-distance migrants one stands out: the Whimbrel.
As birds go, they are among the world’s top super-athletes, avian marathoners making a twice-yearly journey from Arctic tundra to as far south as Tierra del Fuego.
Their plumage speaks to camouflage: brown above, light below, with some barring that makes them blend in among marsh or upland grasses. They are large, long-legged birds, tall, with a wingspan of over 30 inches. Size aside, they look like many other shorebirds. But a long, downcurving bill instantly identifies them as one of the curlews. This angled mandible makes them quickly recognizable, even at a distance. Cautious, as they stalk their prey on a marsh or sandy flat, Whimbrel have a stately yet unassuming presence.
They look, stop, pick or lunge, seizing their food. Alarmed, they cry out and leap into flight, powerful steady wingbeats speaking to their abilities in the air.
They were once abundant. In 1833 a flock of 1,500 birds was recorded. But after the 1870s the largest flock ever seen numbered only 100. Known back then as the Hudsonian Curlew, Whimbrel were among the many shorebirds to suffer under the hail of lead known as the market-gunning era, when commercial hunters took a tremendous toll.
By the 1890s Nantucket was the best place to find them, but the birds were so wary that they were difficult to hunt. Today, the Migratory Bird Treaty of 1918 is still a major barrier between many birds and extinction. But even so, Whimbrel never completely recovered.
Over the last four years researchers at Manomet (formerly known as the Manomet Bird Observatory) have been tracking Whimbrel on migration, using lightweight satellite transmitters. Whimbrel can fly more than 2,000 miles over the rough, open Atlantic without once stopping to land. They can dodge hurricanes and buck headwinds. Day and night, they beat against the forces of nature for days without food or rest. Their endurance is amazing.
Seen on Nantucket in small groups of two or three or sometimes even a flock of 30 or so, the vast distances they travel make their brief pit stops all the more important. This is where the satellite tracking devices help identify the crucial areas traditionally used by Whimbrel.
Protecting these places also protects the birds. They depend on finding the right habitat, with shelter and food to fuel the journey. Like a roadside service area in the desert, if the gas pumps and the restaurants are closed, and you fetch up there when the tummy and the tank are both empty, life can get very tough, very quickly. To conserve the species, researchers must first find those scattered places where the birds put down to rest and feed.
The curve of the Whimbrel’s bill conforms perfectly to the twist of fiddler-crab burrows. A favorite food, these small crabs with one large and one tiny claw can be found in huge numbers in our marshes in August. One visitor commented that they seemed almost horror-movie-worthy. But they are loaded with fat and protein, a rich source of calories. Although crabs are a favorite, Whimbrel are able to eat a variety of foods, such as clams, marine worms, small fish or even plant material such as flowers or shoots and tubers. One gentleman writing from Panama in 1913 described a flock tip-toeing in a clearing in front of his door in Gatun, catching butterflies.
On the breeding ground they consume and feed their young a tremendous number of insects, such as grasshoppers, crickets, flies and beetles, even spiders. They also forage for fruits such as mountain cranberry, crowberry, blueberry or bearberry, eating the previous year’s crop until new ones appear.
Nesting on mosses, lichens or gravel, finding hummocky sites among the sedges of tundra and taiga, they nest only once a year, laying four eggs. Both parents incubate the eggs and tend the young. Chicks can feed themselves almost immediately, but still require protection.
Adult females migrate first, while adult males remain with the brood until they are nearly ready to fledge. In North America there are two unconnected breeding areas, with a population scattered across parts of Alaska and another along the western shores of Hudson Bay. The latter are more likely to be the ones we see most often in New England. We seldom see birds heading north in spring, but begin to find south-bound migrants in mid-July. Young birds may delay into September, but are usually gone by the end of the month.
But not always. One was seen on a Nantucket Christmas Bird Count in 1998. On Dec. 16, 2018, a late migrant was found in the marsh at the University of Massachusetts Nantucket Field Station. Weather had been generally mild. But the sighting was so unusual that ornithologists were skeptical of the identification. So, on Jan. 18, Brad Winn, director of shorebird habitat management at Manomet, paid the island a visit to try to find the bird.
He verified it thus: “It is a 2018 hatchyear Whimbrel, and has most of its original feathers, grown in a far-off land of tundra somewhere, perhaps Hudson Bay lowlands or the Mackenzie River Delta. The tertials and tail feathers show quite a bit of wear. Body condition was not starving but was lean. It seemed quite healthy based on behavior.”
As observers watched, the bird called, flew well, and even took a bath in the harbor.
But then temperatures plummeted into the low teens and a blanket of ice draped the marsh. Researchers feared this might have either been the end of the Whimbrel or created seriously frostbitten feet and legs. It was well below what the species appeared able to survive.
They wondered, how does a crab-eating bird survive in a frozen marsh, when crabs ought to be in bed, asleep? UMass field station director Yvonne Vaillancourt noted that research had shown more than one species of crab using the marsh, based on elevation, and that the tide gives areas of open water.
This was fortunate. Despite the intense cold snap, the lonely bird was seen again among the sheets of ice Jan. 23. As birders watched, it was clearly foraging: a lunge, and it came up with something in the tip of its bill. It tossed back its head and – down the hatch– it chugged the lump.
There were a few mild days after that but the bird was not seen again. Did it perish? Did it see the error of remaining, and head south? Why was it there so late? Was it part of a late brood? Was it delayed by starvation, or a food bounty too good to leave? Had it suffered from bad weather, temporary injury, disorientation or some other mishap? Was it a result of climate-change warming in the Arctic?
These are the questions that keep us watching and wondering, admiring anew the unexpected marvel of the Whimbrel. But all we can say is, “Wow, that is one tough bird.” ///
Virginia Andrews writes the weekly “Island Bird Sightings” column for The Inquirer and Mirror, Nantucket’s newspaper since 1821, and is a regular contributor to Nantucket Today.
