Arctic TernSterna paradisaea Pontoppidan
Status Common in summer. Breeds. This species arrives in Nova Scotia in the second week of May, a little later than the Common Tern. The earliest report is of two birds collected near the Tusket Islands, Yarmouth County, on 3 May 1956. In summer it is common along the coast where the water is clear and the tidal reach is extensive rather than abrupt but is uncommon to absent in areas where tidal mudflats cause muddy waters. The return passage begins in mid-July and is largely completed by mid September. The latest sighting is of a group of birds at Sable Island on 1 October 1976.
Description Length: 36-43 cm. Adults in summer: Similar to Common Terns; tarsi considerably shorter; legs red; bill red, without black tip. Adults in winter: White fore crowns, black on the head being largely confined to nape; bills darker. Immatures: Similar to winter adults but tails shorter.
Breeding Nest: A depression in the turf or sand, sometimes scantily lined with bits of dried eelgrass or other rubbish, and sometimes without a lining; in colonies, usually mixed with Common Terns. In my experience, islands are selected for nesting rather than mainland beach sites. Eggs: 1-2, usually 2; not readily distinguishable from those of the Common Tern.
Range Circumpolar. In North America, breeds across the Arctic from Alaska to northern Greenland, south to northern British Columbia, Lake Athabaska, James Bay and along the Atlantic coast to Massachusetts. It is known to nest within 850 km of the North Pole (Cooke 1915). Winters off southern Africa and in the Antarctic.
Remarks The Arctic Tern is one of the greatest avian travellers. It leaves our shores in autumn for a trans-Atlantic flight to Europe, where it follows the coast southward to its wintering grounds off southern Africa; juveniles continue south to the edge of the Antarctic pack-ice. The recovery of bands from these birds tells amazing stories. A juvenile banded in Maine on 3 July 1913 was found dead on the Niger River Delta in West Africa in August 1917. Another, banded in Labrador as a downy chick on 22 June 1927 was recovered in France on 1 October that year; only three months old, it had flown across more than 5,000 km of ocean. Another banded in Labrador as a chick on 23 July 1928 was found less than four months later on the beach at Margate, Natal, South Africa.
It closely resembles Common and Roseate Terns (distinguishing field marks are cited under those species).
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