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Arctic tern
The Arctic tern (Sterna paradisaea) is a tern in the family Laridae. This bird has a circumpolar breeding distribution covering the Arctic and sub-Arctic 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 individual from the Farne Islands in Northumberland with a light level geolocator tag covered a staggering 96,000 km (52,000 nmi) in ten months from the end of one breeding season to the start of the next. These are by far the longest migrations known in the animal kingdom.
Arctic terns are medium-sized birds. They have a length of 28–39 cm (11–15 in) and a wingspan of 65–77 cm (26–30 in), and weigh around 100 g. In the breeding season they are mainly grey and white plumaged, with a blood red beak and feet, a black crown and nape, and white cheeks. The mantle is grey, and the scapulars grey, tipped white. The upper wing is grey with a white leading edge and a narrow blackish trailing edge on the primary feathers; the collar is completely white, as is the rump. The deeply forked tail is whitish, with grey outer webs. In winter, the forehead becomes partly white, and the bill and legs are black. Juveniles also have a partly white forehead, and narrow pale orangey-brown fringes on the grey mantle feathers (unlike common tern, where the mantle feathers are more completely gingery-brown).
Arctic terns are long-lived birds, with many reaching fifteen to thirty years of age, with a record of 31 years. They eat mainly fish and small marine invertebrates. The species is abundant, with an estimated two million individuals. While the trend in the number of individuals in the species as a whole is not known, exploitation in the past has reduced this bird's numbers in the southern reaches of its ranges.
The genus name Sterna is derived from Old English "stearn", "tern". The specific paradisaea is from Late Latin paradisus, "paradise". The Scots names pictarnie, tarrock and their many variants are also believed to be onomatopoeic, derived from the distinctive call. Due to the difficulty in distinguishing the two species, all the informal common names are shared with the common tern.
The Arctic tern has a continuous worldwide circumpolar breeding distribution; there are no accepted subspecies. It can be found in coastal regions in cooler temperate parts of North America and Eurasia during the northern summer. During the southern summer, it can be found at sea, reaching the northern edge of the Antarctic ice.
The Arctic tern is famous for its migration; it flies from its Arctic breeding grounds to the Antarctic and back again each year. The shortest distance between these areas is 19,000 km (12,000 mi). The long journey ensures that this bird sees two summers per year and more daylight than any other creature on the planet. One example of this bird's remarkable long-distance flying abilities involves an Arctic tern ringed as an unfledged chick on the Farne Islands, Northumberland, UK, in the northern summer of 1982 that reached Melbourne, Australia in October, just three months after fledging, a journey of more than 22,000 km (14,000 mi). Another example is that of a chick ringed in Labrador, Canada, on 23 July 1928. It was found in South Africa four months later.
A 2010 study using tracking devices attached to the birds showed that the above examples are not unusual for the species. In fact, the study showed that previous research had seriously underestimated the annual distances travelled by the Arctic tern. Eleven birds that bred in Greenland or Iceland covered 70,900 km (38,300 nmi) on average in a year, with a maximum of 81,600 km (44,100 nmi). The difference from previous estimates is due to the birds taking meandering courses rather than following a straight route as was previously assumed. The birds follow a somewhat convoluted course in order to take advantage of prevailing winds. The average Arctic tern lives about 30 years and will, based on the above research, travel some 2.4 million km (1.5 million mi) during its lifetime, the equivalent of a roundtrip from Earth to the Moon more than three times.
A 2013 tracking study of half a dozen Arctic terns breeding in the Netherlands shows average annual migrations of c. 48,700 km (26,300 nmi). On their way south, these birds roughly followed the coastlines of Europe and Africa.
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Arctic tern
The Arctic tern (Sterna paradisaea) is a tern in the family Laridae. This bird has a circumpolar breeding distribution covering the Arctic and sub-Arctic 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 individual from the Farne Islands in Northumberland with a light level geolocator tag covered a staggering 96,000 km (52,000 nmi) in ten months from the end of one breeding season to the start of the next. These are by far the longest migrations known in the animal kingdom.
Arctic terns are medium-sized birds. They have a length of 28–39 cm (11–15 in) and a wingspan of 65–77 cm (26–30 in), and weigh around 100 g. In the breeding season they are mainly grey and white plumaged, with a blood red beak and feet, a black crown and nape, and white cheeks. The mantle is grey, and the scapulars grey, tipped white. The upper wing is grey with a white leading edge and a narrow blackish trailing edge on the primary feathers; the collar is completely white, as is the rump. The deeply forked tail is whitish, with grey outer webs. In winter, the forehead becomes partly white, and the bill and legs are black. Juveniles also have a partly white forehead, and narrow pale orangey-brown fringes on the grey mantle feathers (unlike common tern, where the mantle feathers are more completely gingery-brown).
Arctic terns are long-lived birds, with many reaching fifteen to thirty years of age, with a record of 31 years. They eat mainly fish and small marine invertebrates. The species is abundant, with an estimated two million individuals. While the trend in the number of individuals in the species as a whole is not known, exploitation in the past has reduced this bird's numbers in the southern reaches of its ranges.
The genus name Sterna is derived from Old English "stearn", "tern". The specific paradisaea is from Late Latin paradisus, "paradise". The Scots names pictarnie, tarrock and their many variants are also believed to be onomatopoeic, derived from the distinctive call. Due to the difficulty in distinguishing the two species, all the informal common names are shared with the common tern.
The Arctic tern has a continuous worldwide circumpolar breeding distribution; there are no accepted subspecies. It can be found in coastal regions in cooler temperate parts of North America and Eurasia during the northern summer. During the southern summer, it can be found at sea, reaching the northern edge of the Antarctic ice.
The Arctic tern is famous for its migration; it flies from its Arctic breeding grounds to the Antarctic and back again each year. The shortest distance between these areas is 19,000 km (12,000 mi). The long journey ensures that this bird sees two summers per year and more daylight than any other creature on the planet. One example of this bird's remarkable long-distance flying abilities involves an Arctic tern ringed as an unfledged chick on the Farne Islands, Northumberland, UK, in the northern summer of 1982 that reached Melbourne, Australia in October, just three months after fledging, a journey of more than 22,000 km (14,000 mi). Another example is that of a chick ringed in Labrador, Canada, on 23 July 1928. It was found in South Africa four months later.
A 2010 study using tracking devices attached to the birds showed that the above examples are not unusual for the species. In fact, the study showed that previous research had seriously underestimated the annual distances travelled by the Arctic tern. Eleven birds that bred in Greenland or Iceland covered 70,900 km (38,300 nmi) on average in a year, with a maximum of 81,600 km (44,100 nmi). The difference from previous estimates is due to the birds taking meandering courses rather than following a straight route as was previously assumed. The birds follow a somewhat convoluted course in order to take advantage of prevailing winds. The average Arctic tern lives about 30 years and will, based on the above research, travel some 2.4 million km (1.5 million mi) during its lifetime, the equivalent of a roundtrip from Earth to the Moon more than three times.
A 2013 tracking study of half a dozen Arctic terns breeding in the Netherlands shows average annual migrations of c. 48,700 km (26,300 nmi). On their way south, these birds roughly followed the coastlines of Europe and Africa.