Arctic Tern Diet and Size: Feeding Habits, Predators, and Measurements

Arctic Tern Diet and Size: Feeding Habits, Predators, and Measurements

Famous for its incredible annual migration, the Arctic Tern is a small bird with grey and white plumage and angular wings. It travels from Arctic breeding grounds to enjoy the Antarctic summer, flying around 25,000 miles. 

When they reach maturity, they have a full black cap, red legs that are quite short, and a red bill. They are social creatures, feeding and nesting in groups on the ground. These birds often pause their flights to rest on ice, flying with a grace and lightness in their wings.

The Dietary Habits Of The Arctic Tern

Let’s take a look at their primary food sources and the techniques they use to feed on small fish and insects. 

What Does An Arctic Tern Eat?

Arctic terns prey on various small fish species, all generally less than 6 inches in length, including sand eels, capelins and sand lances.

They capture prey by diving from above the water or by skimming just beneath. They also pluck insects from the surface of the water or directly from it. 

While migrating, they commonly forage in groups with other seabirds, following big predatory fish that herd smaller fish to the surface.

What To Feed A Baby Arctic Tern? 

Baby arctic tern’s should be fed small fish such as sand lance, herring, and capelin, which are nutrient-rich and essential for their growth. 

Marine invertebrates like krill and small crabs are also important for protein and fat intake. 

Occasionally, insects like ants and grasshoppers can be included, especially when fish are less available. Frequent feeding throughout the day is necessary to ensure steady growth and development​ 

Breeding Habits Of Arctic Terns

Female Arctic Tern

During mating, the male performs what’s called a “fish flight”, flying while carrying fish and making loud calls (they are capable of shouting even with food in their mouths), before landing and presenting the prey to the female.

Arctic terns choose to nest on sandy or rocky beaches of the far north, where these birds group together in large numbers. Before laying eggs, they form hollows in the sand or gravel. The eggs are incubated in the summertime, from June to July, taking roughly 21 to 22 days. Usually, each female will lay two to three eggs.

At birth, chicks are covered in soft down and have their eyes open. Not fully dependent nor completely independent, they start to wander and check their environment within one to three days. Most chicks can swim at 2 days. Generally, they stay close to their nest.

For the initial 10 days, the chicks are cared for by both parents. They manage to fly after another 10 to 15 days. Arctic terns of both genders start to breed when they are between 3 and 4 years old.

Do Arctic Terns Mate For Life?

Arctic terns stay with one mate throughout their lives. On their migrations, they habitually return to the same places every year.

The Size & Weight Of Arctic Terns

Learning these details will explain how its body makes its extensive flying possible.

How Much Does An Arctic Tern Weigh?

Weighing between 95 and 125 grams, the Arctic tern is a bird of medium size. Its beak and small legs with webbed feet are dark red. This bird has long, slim wings and a deeply split tail, which is common for terns.

Which is around the same length as a Kestrel, though the arctic tern usually has a slightly longer wingspan.

How Big Is An Arctic Tern?

Arctic terns are moderately sized birds, with its body length ranging from 32 to 35 cm (12.5 to 13.7 inches) and its wings stretching from 75 to 86 cm (29.5 to 33.8 inches).

Which makes the arctic tern around the same length as a Kestrel, which has a slightly shorter wingspan.

Are Arctic Terns Under Threat?

Male Arctic Tern

You’ll find the Arctic tern is a common bird, and it has been categorised as a “Least Concern” species on the IUCN (International Union for Conservation of Nature) Red List, meaning it’s not facing extinction globally at the moment.

Historically, this bird faced a lot of hunting, and people collected its eggs, especially in the early 20th century. But today, the number of these birds worldwide is stable or increasing.

Similarly, in the UK, the Arctic tern falls under the protection of the Wildlife and Countryside Act 1981, helping to keep its population stable.

What Eats An Arctic Tern?

Large gulls and invading species like cats and rats, which feed on eggs and chicks, pose the greatest threat to the nesting of Arctic terns.

When it’s not their breeding season, Arctic terns tend to be safe from natural predators, as they are mostly out at sea, away from direct threats.

Where Can I See Arctic Terns In The UK?

In Scotland and Ireland, Arctic Terns often breed on the coast, especially in places like Shetland and Orkney. 

In Wales, their breeding is limited to islands around Anglesey, and there’s a smaller group on the Isle of Man.

SEE ALSO: Arctic Tern Life Cycle: Nest Building To Fledging (and everything in between)

Frequently Asked Questions

What is the size of the Arctic tern?

The size of the Arctic tern varies, with a body length ranging from 32 to 35 cm (12.5 to 13.7 inches) and a wingspan stretching from 75 to 86 cm (29.5 to 33.8 inches).

What does the Arctic Tern eat?

The Arctic tern preys on various small fish species, generally less than 6 inches in length, such as sand lances, sand eels, and capelins. Additionally, they pluck insects from the surface of the water.

What are Arctic Terns’ predators?

The main predators of Arctic terns include large gulls and invasive species like cats and rats, which pose a threat particularly to the eggs and chicks during the nesting period.

Do Arctic Terns sleep while flying?

Arctic Terns do sleep while they fly, a special skill that helps them manage their long travels and migrations. This talent is key to their yearly trips between the Arctic and the Antarctic and back. This saves energy and helps them survive their tough journey. 

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