Hardly any bird in Europe is so aggressive and belligerent as the Arctic tern. They are fiercely defensive of its nest and brood. Arctic terns breed in colonies on coasts, islands and occasionally inland on tundras near water. It often forms mixed flocks with the Common Tern. One Arctic tern lays from one to three eggs per clutch, most often two.
Arctic terns protect their eggs and young chicks by dive-bombing any humans who get too close. Even cars or sheep are not spared by the terns. Arctic terns are not friendly creatures, in fact, they are very aggressive, and show no fear of humans.
We have also been attacked by these birds many times in Iceland. If you do not want them to peck your head, you can put your arm, a stick or if you want your camera up in the air, because they will attack the highest point on you.