Shorebirds are migrating
By DON MORROW
I was down at Lighthouse Pool at St. Marks National Wildlife Refuge last month. High tide had pushed shorebirds in and more than 2,000 of them were feeding in the pool’s shallow waters. There were Short-billed Dowitchers, Black-bellied Plovers, Willets, and both Greater and Lesser Yellowlegs, but more than 90% of the birds were Dunlins. Suddenly, they all began to fly as a Merlin swooped in. I watched as the flock twisted, turned, and split up. There were brief white flashes as thousands of Dunlin simultaneously showed their light bellies before spiraling away.
The Merlin was persistent and kept up the chase, its flight path corkscrewing across the surface of the pool. It was, however, eventually unsuccessful and flew off down the coast to seek other victims. Most of the pool’s shorebirds had simply flown around in circles and they landed when the Merlin left. This was just a normal part of life for them.
The Dunlin that comprised most of that flock are the most common shorebird at the refuge in winter.
They are a medium-sized sandpiper, just a bit chunky, but weigh only two ounces. Dunlin are on the refuge from October through the middle of May and are already in their winter plumage when they arrive. They are a dull grayish brown above and whitish below and have a slightly decurved black bill. They were once called Red-backed Sandpipers, because in breeding plumage, they have a bright rufous back along with a black belly patch. Some Dunlin are already beginning to molt into breeding plumage.
Dunlin are a cosmopolitan species and breed in the arctic throughout the world. The hudsonica subspecies that we see at the refuge are from a population that breed in central Canada, roughly from Victoria Island down to the southwest coast of Hudson Bay. In winter they feed on tidal flats and eat polychaete worms and small shellfish. On their breeding grounds, they mainly eat insect larvae, although female Dunlin eat Lemming teeth and bones as a calcium source for egg laying.
Shorebirds are active right now. Dunlin numbers have dropped by 40% from their winter high as birds begin to stage northward, but there are still 2,300 Dunlin on the refuge. Short-billed Dowitcher and Semipalmated Plover numbers have jumped as migrants from further south move through and if you look closely, you’ll see that our Willets are now mostly the eastern subspecies. Most of the western Willets are gone.
Several shorebird species that are here only on migration, Stilt Sandpiper and Piping Plover, are passing through and our summer breeders are returning. Three pairs of Black-necked Stilts are on the back end of Stony Bayou 2 where they have nested in past years, Wilson’s Plovers have begun to show up and an uncommon refuge breeder, Killdeer, already has two fledglings running on the mudflats at East River Pool.
I like shorebirds. They are one of my favorite groups of birds. They are creatures of wind and tide with continent-spanning migratory flights that connect us to the arctic and the pampas of Argentina. If I was a shorebird, I would want to be a Pectoral Sandpiper.
Come down to St. Marks and figure out what kind of shorebird you want to be.
Don Morrow can be reached at donaldcmorrow@gmail.com.