The Arctic tern (Sterna paradisaea) is a medium-size seabird that has inspired biologists not only for its elegant style but also for making the longest migration of any living animal. It is widely distributed in many parts of North America, Europe, and Asia including Arctic regions. Arctic terns are highly migratory and the only bird that travels as much as 70,000 kilometers a year. The total distance they travel during their lifetime is three times the distance between the earth and the moon.
Arctic Tern Facts
- Adult arctic terns reach a length of about 28–39 cm (11–15 in) with the wingspan measuring up to 65–75 cm (26–30 in).
- The average weight of arctic terns is about 86–127 g (3.0–4.5 oz).
- They are mainly distinguished by their light grey plumage and red beak. There is a black crown covering its forehead. The bird’s feet and legs are also red. Young terns show white forecrown.
- Arctic terns have got forked white tail and white cheeks.
- They have got great stamina.
- They are thought to have longer lifespans in comparison to other birds.
- Arctic terns are most likely to have circumpolar distribution and are mainly found in the temperate regions of Canada, Eurasia and North America.
- Terns spend most of the time in the southern Atlantic and Pacific mostly on the Antarctic ice pack.
- They spend winter at sea typically on the northern Antarctic ice.
Behavior & Migration
- The minimum distance they cover during their migration between Arctic and the Antarctica is about 19,000 km (12,000 mi). They travel so much that these birds are able to enjoy two summers in a year.
- Arctic terns cover the maximum distance of 81,600 km (50,700 mi) per year in Greenland. However on average they migrate 70,900 km (44,100 mi) between the breeding grounds each year.
- During her entire lifetime arctic terns travel as much as 2.4 million km (1.5 million mi).
- Terns are likely to gather on their breeding sites in large numbers. Each flock consists of hundreds of thousands of birds. They will fly to as far as the southern breeding sites from the northern sites.
- They typically migrate in small groups.
Feeding Ecology & Diet
- Arctic terns are primarily carnivorous. They rely on fish and marine crustaceans. Fish is the essential part of tern’s diet.
- Arctic tern’s diet also consists of sandlances, shrimps, migrating insects, small squid, capelin, herring, and cod. They also eat marine crustaceans such as crabs, krill, and amphipods.
- Sometimes terns dive as deep as 24 inches down the sea to catch haddock, butterfish, herring, sprats, and salmon.
- During the breeding season, they are likely to feed on sand eels.
- Terns also supplement their diet with berries, fruits, mollusks, worms, and breeding insects.
- They will consume insects that are on the surface of water. Terns have got the ability to catch insects in the air.
Reproductive Biology & Habitat
- The arctic tern is a monogamous bird as it pairs for life. It is thought to use the same breeding site again in the next year.
- The breeding mostly occurs between May and August.
- They become mature in about 3 – 4 years age.
- Arctic terns breed in colonies and they mostly choose tundra and islands for their breeding habitats.
- A female lays 1 – 3 eggs in each clutch.
- They are extremely aggressive when it comes to defending its nests or chicks. It might not even scare of large predators like foxes or cats.
- Terns usually lay eggs in a depression on the ground. Sometimes the depression is lined with grasses sometimes not. The arctic terns are camouflaged.
- Both parents incubate the eggs that last about 20 – 24 days.
- Eggs hatch in about 3 – 4 weeks and chicks fledge out after 21 – 24 days.
- Hatchlings mainly rely on fish. Males bring them large amount of food as compared to females.
- Young terns remain in the nest for 2 – 3 days.
- The average lifespan of arctic terns is 30 – 34 years in the wild.
- Predators of arctic terns are foxes and cats.