Ruddy turnstone (Arenaria interpres)
The turnstone is a distinctively coloured wader with a short, pointed bill. The turnstone breeds in the circumpolar Arctic as well as in north temperate regions. In north-western Europe it is found from the southern coasts in Scandinavian to Svalbard and northern Russia. In the breeding season the turnstone usually prefers stony ground with sparse vegetation close to the sea.
The turnstone is a distinctively coloured wader with a short, pointed bill. Adult birds are approximately 23 cm long and weigh between 80g and 130 g. The male has the most distinctive markings, with a variegated chestnut-brown and black back, brown-black wings with white patches, a white head with dark streaks on the crown and black markings on the sides of the head. The breast is black and stands out in contrast to the white belly. The legs are orange. The female has duller plumage and has a more brown-grey back, and brown-streaked markings on the head. In winter plumage both sexes are less colourful. The black markings on the head and breast are replaced with brown-grey, while the feathers on the back and upper sides of the wings are brown-grey with brown-yellow edges. Juveniles resemble the adults in winter plumage, but have rusty-yellow edged feathers on the back. The call is a staccato "tuk-a-tuk" or a warbling "tuk-tuk-tuk-tuk".
The turnstone breeds in the circumpolar Arctic as well as in north temperate regions. In north-western Europe it is found from the southern coasts in Scandinavian to Svalbard and northern Russia. Two sub-species are recognized. The Svalbard population belongs to the nominate form A. i. interpres. The other sub-species A. i. morinella breeds in arctic Canada north to about 74o N. In Svalbard, the turnstone is found on most coastlines throughout the archipelago. Highest densities are found along the fjords on the western side of Spitsbergen. Birds from Europe and Greenland winter along the coast of southwest Europe, south to West Africa. The turnstone arrives in Svalbard toward the end of May or early June and migrates southwards again during August or early September.
In the breeding season the turnstone usually prefers stony ground with sparse vegetation close to the sea. They breed in pairs or in loose colonies of a few pairs. The breeding territories are often re-occupied by the same birds in successive years. Few predators threaten the turnstone at the nest compared to other waders. This is due to a strong anti-predator behaviour from both parents which is successful against most avian predators. However, polar foxes and glaucous gulls still cause significant mortality of eggs and chicks. On the tundra the diet consists mainly of insects, though plant material can be important before insects become available in early summer. When feeding in the tidal zone small gastropods, crustaceans and insects are the most important prey. The turnstone uses its strong neck and bill to turn over seaweed and small stones in order to get access to food items. It also eats the eggs of the arctic terns and other ground-nesting tundra birds. Outside the breeding season the turnstone often feeds along stony and rocky coasts in mixed groups with other waders.
Life history and reproduction
The nest is a shallow depression in the ground which is lined with leaves and other plant material. The four pear-shaped eggs are grey-green with strong dark brown speckles and blotches. They are incubated for about 22 days, first by both sexes, but towards the end of the incubation period mostly by the female. The young leave the nest within 24 hours after hatching and are protected by both parents until they are fledged after about three weeks. The young birds become sexually mature at two years of age. The highest age recorded in Norway (including Svalbard) is 13 years.
Management status and monitoring
The Svalbard breeding population has been estimated to be between 50 and 500 pairs. No reliable census of the breeding population has been conducted, and the population trend is unknown. The European breeding population is estimated to be up to 81,000 pairs, and is thought to be stable. If disturbed by humans an incubating turnstone will leave the nest and stay away for a considerable period of time, leaving the eggs or young susceptible to predation or cooling.
MOSJ indicators (Environmental Monitoring of Svalbard and Jan Mayen):
Awaiting results from MOSJ…