I live on the Delmarva Peninsula. It is aptly named since it encompasses Delaware to the east, the Eastern Shore of Maryland to the west, and Cape Charles Virginia at its southern tip. It’s bordered by Delaware Bay and the Atlantic Ocean to the east and the Chesapeake Bay to the west. Delmarva is a flat, rural lowland with abundant farms and tidal wetlands. There is not a rock in sight as the glaciers of the last Ice Age never made it this far south. All in all it’s a perfect stopover and refueling site, or even a final destination for migrating shorebirds. There are 50 species of shorebirds that breed regularly in North America and 217 species worldwide, just a small percentage of the total avian population of over 10,000 species.
Piping Plover (Charadrius melodus) click on any photo to zoom
The spring and fall migrations of shorebirds are completely different animals. In spring the birds with raging hormones are making a mad dash to arctic and sub-arctic breeding grounds. They follow the 35 degree isotherm to ensure liquid water and insects upon arrival. Males and females must arrive at nearly the same time to mate, establish territories, build nests, lay eggs, and raise the young, all during the short, two-month arctic summer. Fall migration, on the other hand is a much more leisurely trip south spanning several months from late June through November.
Ruddy Turnstone & Black-bellied Plover (Arenaria interpres & Pluvialis squatarola)
The birds that abandon the arctic first and head south, even in late June, are the unsuccessful breeders and nesters. If their first attempt fails due to weather, predation, etc., there is simply not enough time to try again. Better to head south early and hope for better luck next year. Some species send one of the parents south (either the male or female) as soon as the eggs are laid leaving the other to sit on the nest and raise the hatchlings. Luckily shorebird chicks are more precocious than most birds walking, feeding themselves, and flying at an young age. The abiding parent will also migrate relatively early leaving the offspring behind to gain strength. Amazingly the juveniles will head south one month later, often flying thousands of miles to their wintering grounds without any adult supervision.
Black Skimmers (Rynchops niger)
There has been speculation about the reason for an early fall migration from the tundra, even though there are still abundant insects and other food sources. Some have suggested that the ancestors of these birds were tropical or neo-tropical and only began migrating northward to find new and safer breeding grounds as the glaciers retreated and climate warmed at the end of the Ice Age. Thus, their hearts are really in the south, to which they return to ASAP when their biologic duty is done.
Wilson’s Plover (Charadrius wilsonian)
There is species-specific timing to the fall migration. After the non-breeders, you’re apt to see adult Least and Semipalmated Sandpipers, Yellowlegs, and Dowitchers passing through the Mid-Atlantic region as early as the first of July. There is a somewhat predictable parade of following species, with Dunlins being an example of a late migrant, peaking here in October and November.
Long-billed Dowitcher (Limnodromus scolopaceus)
August is a popular month for observing the shorebird migration as most of the other bird groups have not yet felt the call. Just be prepared for some confusing fall plumages. Some will still have their breeding plumage while others will be in winter garb or a combination of both. Add in the juvenile plumage and potential sex differences and you have some real ID challenges. There’s also always a chance you might see a vagrant, often a lost juvenile far off course. If you need a good reference book for these birds I recommend “The Shorebird Guide” by O’Brien, Crossley, and Karlson.
Black-necked Stilt (Himantopus mexicanus)
You often hear of the amazing distances covered by these migrating shorebirds. Hudsonian Godwits are thought to fly 8,000 miles NON-STOP between breeding and wintering grounds. Other shorebirds “choose” a more conservative approach and forgo the longer trip to Central and South America. The Piping Plover, for instance breeds along the Atlantic seaboard from Massachusetts to Georgia and winters in Florida. Wilson’s Plover both breeds and winters in Florida. The Purple Sandpiper is the most hardy of the “locals” wintering along the rocky Atlantic coast all the way up to southern Newfoundland.
Sanderlings (Calidris alba)
The ubiquitous and seemingly mundane Sanderling has its own migration story. This small wave-chasing shorebird is seen in flocks on virtually every sandy beach world-wide. It lacks a hind toe as a special adaptation allowing it to outrun the surf. These birds breed far to the north in the arctic islands of Canada, Greenland, or Siberia and in this hemisphere choose various temperate wintering shorelines in both North and South America. While some of Sanderlings choose a short migration route, ornithologist have discovered that others circumnavigate the entire Western Hemisphere, leaving the breeding ground in the fall and flying along the Atlantic coast to Chile and Peru. In the spring they return north along the Pacific coast and central corridor, finally ending up at their original breeding site in northern Canada.
Delmarva shorebird (Erratum maximum)
Our local baseball team, a farm club for the Baltimore Orioles, is appropriately called the Delmarva Shorebirds. It seemed like the perfect name until they chose the team logo–they really needed a birder on that committee. I would have suggested a Sanderling, a Piping Plover, or maybe even a Black Skimmer. Instead they ended up with some stylized nonentity that looks like a cross between a Pileated Woodpecker and a Raven. It’s clearly not a shorebird. C’est la vie.
