Black Turnstone, Arenaria melanocephala

The Black Turnstone, (Arenaria melanocephala), is a species of wading bird in the sandpiper family Scolopacidae. It was formerly placed in the plover family Charadriidae. It is one of two species in the genus Arenaria; the other being the Ruddy Turnstone (A. interpres).

The Black Turnstone is native to western North America and breeds only in Alaska from the Alaskan Peninsula in the south to Point Hope in the north. Most of the population nests in the Yukon-Kuskokwim Delta. It usually nests near the coast but is sometimes also found further inland along shores of rivers and lakes. It is an occasional vagrant to north-east Siberia. The population of this species is estimated at about 95,000 individuals, of which 75 to 80 percent are found in the Yukon-Kuskokwim Delta.

Its winter habitat is rocky shore along the Pacific coast of North America from southern Alaska south to as far as northwest Mexico where it occurs in Baja California and Sonora, and possibly Nayarit. It is occasionally seen inland during spring and fall migration, with some records along the Salton Sea in southern California and scattered sightings in the inland US states of Montana, Wisconsin, Nevada, and Arizona. There is also a rare record of this species on San Cristobal Island in the Galapagos Archipelago.

The adult Black Turnstone is 8.6 to 9.9 inches in length and weighs 3.5 to 6 ounces. Its black bill is about an inch long and slightly upturned. Its legs and feet are blackish-brown with reddish tinge. It is a largely black and white bird in appearance.

The breeding plumage consists of a blackened head and breast. There is a white spot found between the eye and bill, a white stripe over the eye and white flecks on the sides of the breast. Upperparts are blackish-brown with pale fringes to the wing coverts and scapular (shoulder) feathers. The belly and vent are white. A white wing bar, white shoulder patch and white tail with a black band are visible in flight. The lower back and upper tail coverts are white, except for a dark bar across the rump.

Winter plumage reveals a largely dark brown head and breast with little white. The juvenile members of this species are similar to winter adults but are browner with yellowish fringes to the wing coverts and scapulars and a grayish-brown tip to the tail.

A variety of calls are made by the Black Turnstone, including a rattling trill which can be heard throughout the year. This call is higher and less harsh than that of the Ruddy Turnstone. Other calls include a loud, screeching alarm call and a soft, purring call uttered to chicks. The displaying male produces a long series of short notes in flight as well as chirruping trills on the ground.

The diet of the Black Turnstone consists mainly of invertebrates. It primarily takes crustaceans and mollusks during the winter and insects during the breeding season. It will also occasional take in seeds, eggs and carrion. At the breeding grounds it feeds mainly in wet meadows with sedges. In winter, it mainly feeds along rocky coasts, but will also feed on beaches, mudflats, and man-made structures such as jetties and breakwaters. It uses its bill to turn over stones, algal mats and other objects in search of its prey.

It arrives to breeding grounds between early May and early June; males arrive first. These birds often return to the same territory and pair with the same mate year after year. The nest is a scrape dug by the male, usually located amongst sedges or grasses or under willows. The female deposits typically four olive or pale green eggs with darker spots. The eggs are incubated by both parents for 21 to 24 days. The young are precocial (well developed) and are able to leave the nest and can feed themselves soon after hatching. They are able to fly well after 25 to 34 days.

Image Caption: Black Turnstone, Arenaria melanocephala. Laguna Beach, CA, USA. Credit: Davefoc/Wikipedia (CC BY-SA 3.0)