Sanderling

Sanderlings breed in the Canadian Arctic, usually on tundra near the coast. They winter along coastlines in the southern US and as far south as southern South America. During migration, sanderlings can be found along both the Atlantic and Pacific coasts of North America.

Sanderlings can be observed in New Jersey during their migration between their breeding grounds to the north and the wintering grounds to the south. They can be seen in New Jersey in the spring as they fly north and in then in the fall as they fly south. They prefer to migrate along the Atlantic Ocean and Delaware Bay coastlines where they can stop to feed along their migration. They prefer sandy beaches during migration, but they will also use mud flats and shorelines of lakes and rivers.

This species is often observed along the shoreline, darting to and from the ocean waves, as they search for food along the wet sand. With their long beak, they probe along the shore and mudflats for small invertebrates such as small crustaceans, small mollusks, and marine worms. Horseshoe crab eggs are an important source of food for sanderlings during their migration north in the spring.

Sanderlings will feed at any time of the day and at night during the non-breeding season. During the breeding season, sanderlings feed on adult insects and their larvae.

Sanderlings migrate in flocks but may become territorial during the breeding season. The breeding season begins in June to July. They nest on the ground, usually within sight of a marshy pond.

The female lays four eggs and both adults take turns incubating them for 24-31 days. The male will sometimes incubate one clutch while the female will lay a second clutch. The young are precocial and are cared for by both parents. The young will leave the nest soon after hatching, will be able to fly at 17 days old, and will be independent of their parents at 23-24 days old.

Because they nest on the ground in the open tundra, they may fall prey to foxes or predatory birds. They rely on their camouflage to keep them safe from predators.

The sanderling’s population has been declining in recent years. Although it is not known exactly why they are declining, possible causes may be severe weather at their breeding grounds, climate change, loss of prey during migration, or some combination of all of those. This species is listed as Special Concern in New Jersey during the non-breeding season only.

Since 1986, shorebird surveys have been conducted annually by the New Jersey Endangered and Nongame Species Program along Delaware Bay. This survey is one of the longest running surveys of shorebirds in North America. Like other species of shorebird, populations of sanderlings have declined during the survey period. From a peak count in 1986 of over 425,000 individuals, only just over 115,000 individuals were observed in 2008.

Conservation action in New Jersey has focused on shorebird prey during their northward migration. In 2007, the harvest of horseshoe crabs in New Jersey was banned to increase the crab eggs available to shorebirds, including the sanderling and the more imperiled red knot (Calidris canutus).

To protect shorebirds along Delaware Bay, many beaches are closed to the public from the beginning of May into June. These beach closures minimize disturbance to shorebirds so they are not disturbed while feeding. Volunteer “shorebird stewards” educate the public at beaches during spring migration to educate them about the importance of sanderlings and other shorebirds and what is being done to protect them.