Dunlin

The dunlin (Calidris alpina) is a shore wader that is often seen in the United Kingdom, being a familiar sight on the mudflats of river estuaries at low tide. However, it is also seen on inland lake margins and marshes, and it breeds inland, often at some distance from the coast.

The dunlin is at home in the northern tundra, with its breeding range extending to Scandinavia, Russia, Iceland and Greenland. The UK therefore represents the southern end of its range, and its breeding grounds are therefore limited to upland areas of Scotland, Wales and northern England. Breeding pairs are most numerous in the Scottish islands and remote western Highlands and the northern Pennines.


Appearance

The dunlin is quite a small bird at around 18 centimetres (7 inches) in length. It is a compact bird with a short neck that gives it a “hunched” appearance. The bill is quite long, for a small bird, with a downward curve at the tip. The legs are short and black.

The winter plumage (similar in both males and females) is grey above and white below, but in summer the upperparts become chestnut brown, as does the top of the head, and a distinctive dark patch appears on the belly.


Behaviour

The dunlin is a fast flyer, often gathering in large flocks to wheel about in the sky and form constantly changing shapes, much as knots or starlings do. They glide as they come in to land.

They will walk across the mud and in shallow water with head lowered to search for food, and sometimes swim. They feed in groups, often in company with other wading species. At high tide they will gather in large numbers, sometimes in thousands, in fields and saltmarshes close to the shore. When at rest they will stand on one leg facing into the wind with their bill buried in their feathers.

The dunlin has a short, rasping trill, and a purring song in flight.

The diet of the dunlin consists of worms, molluscs, crustaceans and insects, with seeds being added in the autumn. Young birds, before leaving the area of the nest, will feed mainly on mosquito larvae, which are certainly plentiful at that time of year in those locations.


Breeding

Nests are constructed in tussocky grass close to water, the clutch of four eggs being laid in late April or May. In more northern areas, laying may be delayed until June. Both birds incubate the eggs, for up to 22 days. The chicks leave the nest almost as soon as they hatch, but stay close by until they can fly, which will be at about 28 days. The adults leave the breeding grounds for the coast first, with the young birds following in late August.

© John Welford