Common Tern: a two-minute wildlife lesson

Seabirds · day 1 of 7

Five facts

1. Terns are experts at finding their nest. In tests they dug up buried eggs and even found a nest shifted 5 m away.
2. It dive-bombs intruders near its nest but usually swerves away at the last second. It even recognises people and targets familiar ones more.
3. On hot days, a parent sitting on the eggs may fly off to soak its belly feathers, then come back to cool them down.
4. Tiny red oil drops in its eyes boost contrast and sharpen its long-distance sight, which helps when the air is hazy.
5. Sometimes, for no known reason, almost the whole colony takes off in silence and races low out to sea. This is called a "dread".

The quiz

1. What can a common tern do if its eggs are buried in sand?

• Lay new eggs right away
• Find and dig them out (correct)
• Leave the colony for good
• Wait for the wind to uncover them

Tests show terns can locate and uncover buried eggs, even after the sand is smoothed over.

2. Which people do common terns attack most fiercely?

• Strangers
• People wearing red
• Only children
• People they know (correct)

Adults can tell people apart and attack familiar ones more intensely than strangers.

3. How does a parent cool its eggs on a hot day?

• It wets its belly feathers in water (correct)
• It buries them deeper
• It fans them with its tail
• It moves them into the shade of a rock

It may fly to water to soak its belly feathers, then return to the eggs.

4. What do the red oil drops in a tern's eyes do?

• Let it see in total darkness
• Protect its eyes from salt
• Sharpen its distance vision (correct)
• Let it see behind its head

They improve contrast and sharpen distance vision, especially in haze.

5. What is a "dread" in a tern colony?

• A loud fight between two males
• A silent mass flight out to sea (correct)
• A chick calling for food
• A storm that floods the nests

Nobody knows why, but the terns suddenly fly off together, silent, low and fast, out to sea.

More about the Common Tern

Same week

All lessons

Nature documentaries