Sanderling
This week’s bird is the Sanderling (Calidris alba), a small but plump sandpiper. It is one of 96 species in 15 genera in the family Scolopacidae, commonly referred to as Sandpipers and allies. Sanderlings nest in the high Arctic tundra, but are most often seen along sandy coastal beaches on both the east and west coasts during migration and winter. They are long distance migrants. Some travel “only” 2,000 miles to reach the Northeast coast of the U.S., while others fly further south covering over 6,000 miles to reach wintering grounds in South America.
The picture shown here was taken on February 21, 2020, during our most recent trip to Florida. It was a chilly, windy day along the Atlantic Coast just outside Merritt Island National Wildlife Refuge. Dozens of Sanderlings were gathered along the shore feeding on the edge of the white-capped driven waves. I guess a day like this isn’t much of a bother when you consider all a Sanderling goes through during migration and that it breeds in the open Arctic Tundra.
What it looks like
The Sanderling is an energetic, small shorebird with a short, stout, black bill and black legs and feet. In nonbreeding plumage, it appears rather white headed with white underparts that sharply contrast with the black bill and legs. It has pale-gray upperparts, with a distinctive dark shoulder patch. In flight, it shows bold, white wing-stripes bordered by black. In breeding plumage its head, breast and upper parts are reddish brown to sandy brown while underparts remain white.
One of the other features of the Sanderling is a lack of a hind toe. Check out the pictures shown here – it shows the Sanderlings walking on three front toes. Compare it to the pictures below showing a Red Knot and Semipalmated Sandpipers and several Purple Sandpipers.
Notice the hind toe on these birds? For the Red Knot (left), you can see it as the spur sticking out from the leg toward the tail. For the Semipalmated Sandpiper on the right, it’s the small spur sticking down on the forward leg.
The hind toe is called a hallux, and the Sanderling is the only species among the 96 members Scolopacidae not to have one.
Foraging behavior
As Sanderlings forage along coastal beaches, they seem to engage in a game of tag with each oncoming wave. As the waves come in, they scurry to stay just ahead of the water, turning quickly as the waves recede to pick up any crustaceans or mollusks stranded along the surface or probing just below the surface in search of invertebrates. As they probe in sand or mudflats, they keep their bills shut on the downstroke, opening their bill as they extract it to capture any prey.
Conservation status
For migrating birds to survive, they require three primary types of habitat. They need places to breed, places to spend winters, and places to stopover and “refuel” when migrating between the other two areas.
Sanderlings’ habitat is at risk in all three areas. Climate change has the greatest effect in raising temperatures at high latitudes, include the Sanderlings’ Arctic breeding grounds. Both sea level rise and human modification or destruction of coastal shorelines and wetlands degrades key stopover habitat that Sanderlings rely on to refuel during their long migration. And the same risks also affect the wintering breeding areas. Sanderlings are also at high risk from the effects of oil spills; when Sanderlings come into contact with oil, they are forced to spend a vast amount of time preening to remove the oil from feathers, reducing the amount of time feeding by between 60 and 75 percent.
Fortunately, several states along the coast have acted to conserve habitat. Delaware has declared the lower part of the Delaware Bay a shorebird conservation reserve. Both Delaware and New Jersey have placed limits on horseshoe crab harvests (I’ll say more about the importance of this species in a few weeks when I cover Red Knots). Additionally, several organizations have taken steps to purchase and conserve coastal wetlands. Hopefully continued support for these types of conservation efforts will continue to ensure that future generations will enjoy watching the antics of the energetic Sanderling as it runs, high on its three toes, along the edge of the waves.
That’s it for this week. Next week I’ll talk about Tree Swallows.
If you missed last week’s bird, click here to read about the Common Grackle.