The Arctic Tern - Sterna paradisaea - has a worldwide, circumpolar breeding distribution which is continuous and there are no recognized subspecies. Arctic Terns are long-lived birds, with many reaching thirty years of age.

Migration

The Arctic Tern is famous for its migration. It flies from its Arctic breeding grounds to the Antarctic and back again each year. It can be found in coastal regions in cooler temperate parts of North America and Eurasia during the northern summer. While wintering during the southern summer, it can be found at sea, reaching the southern edge of the Antarctic ice. The species' range encompasses an area of approximately ten million square kilometers. Research using tracking devices attached to the birds was published in January 2010 and showed that the above examples are in fact not unusual for the species. Eleven Arctic Terns that bred in Greenland or Iceland each covered 70,900 km on average in a year, with a maximum of 81,600 km. The difference from previous estimates was because the birds were found to take a meandering course to take advantage of prevailing winds.

Plumage

The adult plumage is grey above, with a black nape and crown and white cheeks. The upperwings are pale grey, with the area near the wingtip being translucent. The tail is white, and the underparts pale grey. Both sexes are similar in appearance. The winter plumage is similar, but the crown is whiter and the bills are darker. Juveniles differ from adults in their black bill and legs, "scaly" appearing wings, and mantle with dark feather tips, dark carpal wing bar, and short tail streamers.

Calls

The species has a variety of calls. The two most common being the alarm call, made when possible predators enter the colonies, and the advertising call.

Food

The diet of the Arctic Tern varies depending on location. They eat mainly fish and small marine invertebrates. In the northern breeding grounds they eat insects.

Breeding

Breeding begins around the third or fourth year. They mate for life, and in most cases, return to the same colony each year. Courtship is elaborate and begins with a so-called "high flight", where a female will chase the male to a high altitude and then slowly descend. This display is followed by "fish flights", where the male will offer fish to the female. Courtship on the ground involves strutting with a raised tail and lowered wings. After this, both birds will usually fly and circle each other. The nest is usually a depression in the ground and the eggs are mottled and camouflaged. Both sexes share incubation duties. The young hatch after 22 to 27 days and fledge after 21 to 24 days. They nest once every one to three years (depending on its mating cycle); once it has finished nesting it takes to the sky for another long southern migration.

Conservation status – Least Concern

Arctic Terns are considered threatened or species of concern in certain parts of their range. At the southern part of their range, the Arctic Tern has been reducing in numbers. Much of this is due to lack of food. However, most of these birds' range is extremely remote, with no apparent trend in the species as a whole. The species is abundant, with an estimated one million individuals.

Birdwatching

These beautiful birds can be seen on the following Aves Birding Tours/Safaris/Adventures: -

Aves Eastern Cape Birding Tour/Adventure.

Aves KZN Birding Tour/Safari/Adventure.

Aves Western Cape Birding Tour/Safari/Adventure.

Aves West Coast Birding Tour/Safari/Adventure.