The Common tern is part of the large gull family and is widely distributed across the world. It is around 30 cm (12 in.) long, has a black cap that covers the eye area, light grey upper parts, white under parts, and a sharp red bill with a black tip. The legs are red-orange. Both sexes are similar. Juveniles have a brownish head, a black bill and dark legs. The common tern is very similar to the Arctic tern.
The Latin name ‘hirundo’ refers to some resemblance with the swallow, although the two species are not related. The common tern is also called ‘sea swallow’ sometimes however. The English name is derived from Old English ‘stearn’.
This tern breeds in colonies that can reach several thousand nests, and might share the nesting site with other tern species or gulls. As with other terns, this species feeds on fish by plunge diving from a short height. They drink salt water, as their anatomy can filter out the salt from the water. Their habitat encompasses lake and coastal marshes and beaches, and small islands.
The common tern was subjected to hunting for its feathers in the past, and sometimes the entire bird was used for hats. In spite of the overall population being stable, there has been a decline in the North American population of this bird in the last decades.
The common tern breeds on PEI and is listed as ‘common’ to ‘very common’, however the nesting sites are vulnerable to predation – by gulls especially, and to human disturbance. When disturbed, common terns might not even go back to their nests. Its breeding range covers most of the northern hemisphere, and the wintering range includes a good part of the coastal areas in the southern hemisphere.