How far do Arctic terns migrate?

Arctic terns complete the longest known migration of any animal, flying roughly 70,000 km per year. They breed in the Arctic (including Iceland) from May to August, then fly south to Antarctica for the southern summer, and back again. Over their 30+ year lifespan, a single tern may travel the equivalent of three round trips to the Moon.

Will Arctic terns really attack people?

Yes. Arctic terns aggressively defend their nests from any perceived threat, including humans. They dive-bomb intruders, striking with their sharp beaks at the highest point — usually the top of your head. Hold a stick, hat, or your hand above your head while walking through nesting areas. They target the highest point and will usually strike that instead of your head.

Where do Arctic terns nest in Iceland?

Arctic terns nest across Iceland in colonies ranging from a few pairs to thousands. They prefer flat, open ground near water — coastal meadows, gravel flats, offshore islands, and lake shores. Large colonies are found at Jökulsárlón, along the south coast, at Lake Mývatn, and on the Westman Islands. Nesting areas are often marked with warning signs.

What do Arctic terns eat?

Arctic terns feed primarily on small fish (sand eels, capelin, sticklebacks) and small crustaceans. They hunt by hovering above the water and plunge-diving to catch prey near the surface. During migration, they also feed on krill and small marine organisms. Their dependence on sand eels makes them sensitive to the same ocean temperature changes affecting puffins.

Arctic Tern in Iceland: World's Longest Migration

The holder of the longest migration of any bird on Earth, flying from the Arctic to Antarctica and back every year — a round trip of up to 70,000 km.

Updated February 1, 2026By the Iceland.org Travel Team

Location

Nationwide

Coastal meadows, lake shores, offshore islands

The Arctic tern (Sterna paradisaea), known as "kría" in Icelandic, is one of the most remarkable birds on the planet. Each year, it migrates from its Arctic breeding grounds to the Antarctic pack ice and back — a round trip of up to 70,000 km, the longest known migration of any animal. Iceland is one of the species' most important breeding grounds, with hundreds of thousands of pairs nesting across the country from May to August. While their aerial agility and endurance are awe-inspiring, Arctic terns are also notorious for their aggressive defense of nesting territories, fearlessly dive-bombing any intruder — including humans — who ventures too close.

Safety + sourcing

Last updated: 2026-02-01

Arctic terns aggressively defend nests. Hold an object above your head when walking near nesting areas and stay on marked paths.

Sources to check

Annual Migration

~70,000 km

The longest migration of any known animal on Earth

Breeding Season

May–August

Nests across Iceland on flat, open ground near water

Lifespan

30+ years

Equivalent to 2.4 million km of migration in a lifetime

What to Expect

Population estimate

An estimated 250,000-500,000 pairs breed in Iceland annually, making it one of the species' most important breeding grounds in the North Atlantic.

Best viewing: May-August

Terns are present in Iceland from early May through late August. Peak colony activity is June-July when eggs are incubating and chicks are being fed.

Specific viewing locations

Large colonies at Jökulsárlón, Vík, Lake Mývatn, the Westman Islands, and Grímsey island. In Reykjavík, terns nest in grassy areas and on urban rooftops near Seltjarnarnes.

Dive-bombing defense

Terns attack anything near nests, striking the highest point. Hold a stick, hat, or your hand above your head for protection. Peak aggression is June through mid-July.

70,000 km annual migration

The longest migration of any animal on Earth—Arctic to Antarctic and back. Over a 30+ year lifespan, one tern may travel 2.4 million km (equivalent to three Moon round trips).

Hovering hunters

Watch them hover motionless above the water before plunge-diving to catch small fish near the surface. Their forked tails and narrow wings make them among the most graceful flyers.

Where to See Them

Arctic terns nest across Iceland wherever suitable flat, open habitat exists near water. Major colonies: Jökulsárlón glacier lagoon (south coast, directly on Route 1, 330 km from Reykjavík); along the coast near Vík (Route 1, 180 km from Reykjavík); Lake Mývatn in the north (Route 1, 100 km east of Akureyri); the Westman Islands (30-minute ferry from Landeyjahöfn); and Grímsey island on the Arctic Circle (3-hour ferry from Dalvík or 25-minute flight from Akureyri). In Reykjavík, terns nest on grassy areas at Seltjarnarnes peninsula (bus route 11) and on urban rooftops. No 4WD required for any viewing location. Nesting areas are usually marked with warning signs—stay on paths.

Best Time to Visit

Arctic terns are present in Iceland from early May through late August. May: Arrival and territory establishment; birds active but not yet aggressively defensive; best month for calm observation. June: Egg incubation and early chick rearing; peak aggressive nest defense begins; colonies are at their noisiest and most active. July: Chicks growing and being fed; dive-bombing at its most intense around nests; excellent photography opportunities from a respectful distance. August: Chicks fledging; defensive behavior subsiding; by late August the entire population begins departing for Antarctica. September-April: No Arctic terns in Iceland—they are in the Southern Hemisphere. For observation with minimal dive-bombing, visit in early May or late August.

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Arctic Tern FAQs

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