Common Tern

Fascinating facts about the Common Tern

• A common tern catches roughly 1,000 fish a day — one every 50 seconds during breeding season — by plunge-diving from 10 metres high at speeds up to 24 km/h. In a single summer, a nesting pair feeds their chicks more than 20,000 fish. This obsessive foraging is what transformed terns from casual hunters into some of nature's most efficient aerial fishermen.
• Common terns navigate between Arctic breeding grounds and African wintering grounds using multiple compass systems wired into their brain: a magnetic field detector, sun-position clock, and star map. Recent tracking shows individual birds return to the exact same nesting colony year after year — some using the same nest site for over 20 years. They accomplish this without maps, GPS, or any instruction from older birds.
• The common tern's courtship is a live performance: males bring fish offerings to females mid-flight, executing synchronized aerial dances with precise wing beats. If a female accepts the fish, they're paired for the season — and often reunite at the same colony the following spring, even after nine months apart on opposite continents. The fish becomes currency for pair-bonding.
• At 2,000 kilometres from the nearest freshwater, common terns possess a functional salt gland above each eye that filters seawater, concentrating salt to 10 times the salinity of ocean water. A single drop of brine drains from their nostril every few minutes. This gland is so efficient they can drink seawater without ever touching land for fresh water during migration.
• In the 1950s, pesticide runoff triggered an ecological collapse: tern populations crashed 50–90% across North America and Europe as DDT thinned eggshells until they cracked under incubating parents. Today, after DDT bans and coastal wetland restoration, common tern numbers have rebounded to pre-collapse levels — making them a proof-of-concept that broken ecosystems can heal when humans intervene.

At a glance

About the Common Tern

As the Common Tern dances across the waves, its slender form and agile wings weave a mesmerizing tapestry of light and motion, its feathers glistening like polished silver in the sunlight. With each effortless glide, it seems to embody the very essence of the ocean's breeze, its cries punctuating the air as it pursues its prey with a fierce and unrelenting passion. In its annual migrations, this diminutive bird undertakes a journey of thousands of miles, a testament to its indomitable spirit and unwavering resolve.

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