oceany: Arctic tern

Evidence: 32 • authority: 88

Common Tern Sterna hirundo and Arctic Tern S. paradisaea hybridization produces fertile offspring. This study provides the first molecular evidence for hybridization between Arctic Terns Sterna paradisaea and Common Terns S. hirundo. We studied a mixed pair (P1; male Arctic Tern and female Common Tern) and its offspring on Penikese Island, Massachusetts, USA in 2007–2015. The pair maintained a long-term pair bond (8 years); its reproductive performance was comparable to that of Common Terns and higher than that of Arctic Terns at the site. Molecular analyses confirmed that all young raised by the pair (at least 5 males and 4 females) were biological offspring. We describe hybrid young and t…

Evidence: 24 • authority: 72

The common raven or northern raven (Corvus corax) is a large all-black passerine bird. It is the most widely distributed of all corvids, found across the Northern Hemisphere. There are 11 accepted subspecies with little variation in appearance, although recent research has demonstrated significant genetic differences among populations from various regions. It is one of the two largest corvids, alongside the thick-billed raven, and is the heaviest passerine bird; at maturity, the common raven averages 63 centimetres (25 inches) in length and 1.47 kilograms (3.2 pounds) in weight, up to 2 kg (4.4 lb) in the heaviest individuals. Although their typical lifespan is considerably shorter, common…

Evidence: 24 • authority: 72

Bird migration is a seasonal movement of some birds between breeding and wintering grounds that occurs twice a year. It is typically between northern and southern regions. Migration carries inherent risks, including predation and other hazards en route. The Arctic tern holds the long-distance migration record for birds, travelling between Arctic breeding grounds and the Antarctic each year. Some species of tubenoses, such as albatrosses, circle the Earth, flying over the southern oceans, while others such as Manx shearwaters migrate 14,000 km (8,700 mi) between their northern breeding grounds and the Southern Ocean. Shorter migrations are common, while longer ones are not. The shorter migra…

Evidence: — • authority: 72

Terns are seabirds in the subfamily Sterninae of the wider gull and tern family Laridae. They have a worldwide distribution and are normally found near the sea, rivers, or wetlands. Terns are treated in eleven genera in a subgroup of the family Laridae, which also includes several genera of gulls and the skimmers (Rynchops). They are slender, lightly built birds with long, forked tails, narrow wings, long bills, and relatively short legs. Most species are pale grey above and white below with a contrasting black cap to the head, but the marsh terns, the black-bellied tern, the Inca tern, and some noddies have dark body plumage for at least part of the year. The sexes are identical in appeara…

Evidence: — • authority: 72

The Arctic tern (Sterna paradisaea) is a tern in the family Laridae. This bird has a circumpolar breeding distribution covering the Arctic and subarctic regions of Europe (as far south as Brittany), Asia, and North America (as far south as Massachusetts). The species is strongly migratory, seeing two summers each year as it migrates along a convoluted route from its northern breeding grounds to the Antarctic coast for the southern summer and back again about six months later. Recent studies have shown average annual round-trip lengths of about 70,900 km (38,300 nmi) for birds nesting in Iceland and Greenland, and about 48,700 km (26,300 nmi) for birds nesting in the Netherlands, while an in…