Arctic terns (Sterna paradisaea) preparing for an aerial attack in Bakkadalur in Arnarfjörður in NW-Iceland.
The Arctic Tern weighs little over 100 grams, but it is a fighter, attacking humans and predatory birds and animals of all kind that disturb it in breeding season. It is also a world-class traveller, that would put Marco Polo to shame. The average tern in its life will travel a distance equal to going to the moon and back—about 500,000 miles (800,000 km). It has circumpolar distribution, breeding colonially in Arctic and sub-Arctic regions of Europe, Asia, and North America (as far south as Brittany and Massachusetts). The species is strongly migratory, seeing two summers each year as it migrates from its northern breeding grounds to the oceans around Antarctica and back (about 24,000 miles) each year. This is the longest regular migration by any known animal. It is also one of the birds that spends most time in the air.
Arctic Terns are long-lived birds, with many reaching thirty years of age. They eat mainly fish and small marine invertebrates. The species is abundant, with an estimated one 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 range.