Length: 33 – 36 cm
Wingspan: 76 – 85 cm
Weight: 86 – 125 g
In breeding plumage Arctic terns are pale grey with slightly pale underparts and a white rump, vent, and tail with long streamers. They have grey inner webs on the wings and a long narrow black line along the tips of the outer primaries.
The forehead and crown are black, and they have a small white patch on their cheeks. The bill is red, the eyes are dark brown, and the leg and webbed feet are red. Both male and female look similar.
Outside of breeding season Arctic terns have a white forehead and black bill, legs, and feet.
Juveniles have darker upperparts and brown-tipped feathers on the mantle and inner wings. The head is similar to the adult in non-breeding plumage, and they have and pink bills, legs and feet with some black patches.
Arctic terns nest in colonies and will return to the same breeding grounds each year. Their build their nest in a hollow in the ground in short grasses, sand or gravel away from water.
They lay 1-3 eggs, which are pale olive in colour with darker markings that camouflage them well against the ground. Both male and female Arctic terns will sit on the nest. Eggs are incubated for about 25 days and chicks will fledge at about 21 days.
Although juvenile Arctic terns will learn to feed themselves independently of their parents after a month they will fly south to winter with the help of their parents.
Arctic terns feeds mainly on small fish but will also eat crustaceans, molluscs and insects.
On land they will feed on caterpillars and worms and occasionally berries in early spring.
Where to see them
Breeding Arctic terns can be found in Northern England, Scotland and north Wales mainly on islands such as the Farne Islands or the Northern Isles. During the spring passage they can also be seen on inland reservoirs.
European visitors start to arrive back from the Antarctic in May with northernmost birds getting back in June. They will start their migration south in late July and August.
Did you know?
Arctic terns make the longest migrations of any bird travelling about 70 km a year which adds up to an impressive 2.4 million km over its lifetime.