Terns are water birds from the family Sternidae and are expert fish catchers. There are generally considered to be forty five separate species of terns worldwide. Generally smaller than gulls but with long tails, thin bodies and short legs, they are long distance migrants.
Similar in size to the Arctic Tern, the summer plumage of the adult common tern is predominantly silver grey on the upperparts and pale grey on the underparts. A prominent black cap extends from the base of the upper mandible through the eye and across the head to just above the nape. The chin and face are white and the long thin bill is bright red with a black tip. The long primary flight feathers are a dark grey to black contrasting with the paler short primaries. The tail feathers appear as a similar length to the wing tips when folded with the bird in an upright stance. The upper tail and rump are white and the tail is forked with the longer outer feathers edged black. There is a wide dark bar on the underwing trailing edge and a white translucent patch on the underwing from the tips of the secondary flight feathers towards the flank. The neck is relatively long which is more apparent when the bird is in flight. The legs and webbed feet are a bright red. In winter plumage the forehead and lores, the area immediately in front of the eyes extending to the bill, are white whilst the rest of the cap remains black. The bill is black and the shoulders are a dark grey as are streaks which appear on the outer wing areas. Male and female birds are similar. Juvenile birds are grey in the main but with brown or light ginger barring to the upperparts, a dark grey nape and greyish brown crown with buff coloured forehead. The shoulders are dark, similar to the adult’s winter patternation and the rump, pale grey. The bill is dark grey with a pale pinkish base to the lower mandible and the legs are a light browny pink.
Common Tern stood on branch in water
Common terns use a wide range of vocalisations and are able to identify chicks and siblings by their call. An alarm call similar to ‘kee – yah, kee – yah’ will often silence an otherwise noisy flock or nesting colony often accompanied by a shorter, ‘kyar – kyar – kyar’. On approach to a nest, particularly if returning with food for the young, the adult will issue a, ‘keearr’ sound alerting the nest occupants of the imminent arrival. In social interactions with other terns a simple ‘kik’ or ‘kik – kik’ if often used.
Common Tern Call / Flight Call
Johan Södercrantz, XC657401. Accessible at www.xeno-canto.org/657401.
Common Tern calling
Predominantly a fish eater, the common tern will also feed on molluscs, crustaceans and insects. Almost all food is taken from the water with the bird either hovering then diving down to snatch its prey from beneath the water or simply swooping down and snatching it from the surface.
Pair of Common Terns passing fish
Common terns are migratory and breed across much of the mid Palearctic region from Sweden, east across Russia and through Kazakhstan to Kamchatka and Central and Northern China. There are also breeding populations on the islands in the Atlantic off the Northwest coast of Africa. Within North America they breed throughout central and Southeast Canada, south to the Great lakes and into the North East of the USA. During the winter, Eurasian breeding terns migrate south to the coastal regions of Africa, Indonesia, Malaysia, Papua New Guinea, the South Pacific Islands and the North and East coast of Australia. Those that breed in North America travel south along the Pacific coast of South America as far as Peru, across the islands of the Caribbean and down the Atlantic coast to Argentina and beyond.
Common Tern in flight
Common terns generally inhabit coastal regions although, unlike most members of the tern family, during the breeding season they can also be found great distances inland provided they have close access to rivers, lakes and reservoirs. In the main when they migrate to tropical and sub-tropical regions they confine themselves to coastal areas and spend much of the day fishing out at sea. They are a social bird frequently seen in large flocks or colonies, roosting on sandbars, offshore islands or salt and fresh water marshlands. They are extremely similar in appearance to the Arctic and Roseate Terns and careful observation of plumage, behaviour, location and voice is required in order to tell them apart.
Common Tern feeding Juvenile
There are three sub-species of common tern with Sterna hirundo hirundo being the most populous and occupying the largest geographical area covering North America, Europe and Central Asia. Sterna hirundo tibetana breeds across Central Asia to the Tibetan Plateau and differs slightly from the nominate in that both its belly and back are a much darker grey in colour. Finally, Sterna hirundo longipennis, which is monotypic and breeds from Eastern Siberia through to North East China and migrates south to Australasia. This bird is similar in plumage to Sterna hirundo tibetana with the added anomaly of having a black bill. This latter characteristic easily identifies it within North America where it can be found as a vagrant to Western Alaska.
Common Tern sitting on nest built in the sand dunes
The breeding season is commonly from late April through to June when nests are constructed on the ground, normally a natural hollow or scrape, lined with vegetable matter or surrounded with seaweed and stones. Frequently large colonies of common terns will nest on offshore islands of sand, earth or gravel. One clutch, averaging 2 – 3 buff coloured eggs with dark splodges or streaks, are laid annually and incubated for up to three weeks by both parents. Once hatched, chicks can stand and walk within a few hours and will wander from the nest after two to three days although they are still fed by their parents. Fledging occurs between twenty two to thirty days from hatching.
Common Tern feeding chicks
Predation, particularly from other birds is common around nesting sites. On achieving adulthood, common terns can expect to reach up to ten years of age.
Family:Gulls and terns
31cm to 35cm
77cm to 98cm
90g to 150g
Named in honour of the French naturalist and ornithologist, Jean Victor Audouin (1797 – 1841) the Audouin’s gull is one of the world’s rarest and is limited in the main to regions within and surrounding the Mediterranean Sea.
Until fairly recently yellow-legged gulls were considered a subspecies of the caspian gull or the herring gull. In 2007, the British Ornithologists’ Union first listed it as a distinct species with key differences in appearance and distribution range from similar-looking gulls.
Sandwich terns are migratory seabirds that breed at large nesting colonies along the warm-water coasts of Europe, parts of the south-eastern United States, the Caribbean and as far south as Patagonia in South America. Their distinctive yellow-tipped bill and shaggy black crest make them relatively unmistakable alongside similar seabird species.
Roseate terns have a wide distribution range, and are found on six continents around the world. However, numbers have declined dramatically in some regions, leading to conservation concerns over the long-term survival of the species.
Despite its name, the Mediterranean gull is not limited to coastal waters of southern Europe, and is widespread on the Atlantic and Black Sea coasts, as well as in coastal regions and inland reservoirs of England and Wales.
A tiny, but feisty, seabird, the little tern undertakes epic annual migrations of up to 10,000 km (6,000 miles) between breeding grounds along the UK coast to winter territories in West Africa. Further east, little tern populations complete similar journeys from China and Japan to Australia each year.
Little gulls are small, tern-sized seabirds that breed mainly in Central Asia, but are occasionally reported as vagrant breeders in North America and may be seen in passage around coastal areas of the UK, and rarely reach the United States and Canada.
Lesser Black-Backed Gull
The Lesser Black-backed Gull is one of many attractive ‘white-headed-gulls’ from the Larus genus. Common in the UK throughout the year, these migratory seabirds also visit the eastern half of the United States each winter.
The Kittiwake is an attractive, short-legged gull that breeds on rocky cliffs along the UK’s coastline. These birds disperse each winter to forage out over the open ocean.
Iceland Gulls breed exclusively along the rocky coastlines of north-east Canada to Greenland. Winter migration south occurs, with temporary visitors arriving along both Atlantic and Pacific coasts of the United States, and to coastal areas across north-western Europe.
A familiar bird of the coast, the bold and long-lived Herring Gull is a fascinating seabird in decline.
Great Black-Backed Gull
The Great Black-backed Gull is the world’s largest gull and one formidable seabird. This impressive species lives and breeds along Northern Hemisphere shores on both sides of the Atlantic.
A large, pale gull species, the Glaucous gull breeds across the Arctic, where it hunts for fish, birds and small mammals and scavenges for carrion. Known for their intolerance of sharing a food source with other birds, Glaucous gulls can be physically aggressive as well as highly vocal when approached.
There are four sub-species of the common gull with the European variant being the nominate. The other three are the Russian, Kamchatka and American, which are all predominantly confined to the geographical region attributed by their name. There are subtle differences in plumage and overall size of bird between sub-species.
The title of Black-headed Gull is rather a misnomer for this bird as its head is not black but a dark brown colour and only in adult birds during the breeding season. It is not present during the winter months or in other plumages. Unlike many gulls it is not restricted to coastal regions and is widespread inland in both rural and urban areas.
The Black Tern is a small, graceful seabird that nests far from the ocean. These birds switch between radically different habitats in the breeding and non-breeding seasons, but habitat loss inland has caused their numbers to plummet since the mid-1900s.
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