Common and Arctic Terns---Sterna ssp.

Terns belong to the family Sternidae and have a world wide distribution. They are placed in the Order of birds known as the Charadriiformes, which is a diverse family of small to medium birds, it includes 350 species and has members in all parts of the world. 

Most Charadriiformes live near water others are pelagic {sea birds}, a few are desert species and a handful inhabit thick forests. Common terns are placed in the genus Sterna. This genus includes the common tern , the Arctic tern and the Roseate tern. The common tern is a sea bird, this bird has a wide distribution breeding in temperate and sub Arctic regions of Europe, Asia and east and central north America. It is a prominent migratory species  wintering in the subtropical and tropical oceans.

In his book British Birds in their Haunts, C A Johns 1811-1874 states--" On those parts of the coast where the common tern is abundant, no sea bird is likely to attract the notice of the visitor than the common tern. It is less in size than any of the common species of gull which it is often confounded by the observant.  It is more lively and active in motions, not ordinarily flying in circles, but, if I may use the expressions, "rambling" through the air, frequently diverging to the left and right, and raising or depressing itself at frequent intervals. These characters alone are sufficient to distinguish the tern from any gull, but it presents yet more striking features; its tail is elongated and forked like that of a swallow, and from this character rather than from its flight it is commonly known as the sea swallow.

" The way it takes its prey is greatly different from that of the gulls, suddenly it descends and plunge dives into the water making a splash, but not disappearing. In an instant it ascends again, eating any small fish it has caught on the wing or taking it back to the shore"  Common terns eat fish and insects caught on the wing. 

Common Tern Sterna hirundo flying {Germany }

Courtesy of Andreas Elchier  CC BY-SA 4.0 License.

Description of the common tern.

The length of the bird is 31-35cm { 12-14 inches} with a wing span of 82-95cm { 32-37 inches}  weighing 90-150g { three and a quarter to five ounces} 

The bill of this bird is a moderate red colour with a black tip it has a black cap and black on the back of the head. The upper parts are pale grey, brown at the tips; the tail is much forked, not longer than wings, white, the two outer feathers on each side are dusky. Under parts, white, tinged with grey on the breast. Feet and legs are red. Feathers on the wing are dark at the tips.

In relation to its body size, the wings are medium long, tail medium length, neck medium, bill medium, legs are very short. they have a bouyant, rather bobbing flight with measured up and down, wing beats. Can swim, walks awkwardly on land. They are longed lived birds up to 20 years. 

Common tern

Photograph courtesy of Kirk Rodgers CC BY-SA 3.0 License

Common tern in flight 

Photograph courtesy of Kirk Rodgers CC BY-SA 3.0 License.

The common tern feeds in coastal waters, rivers and lakes. They breed on coasts, islands, salt marsh and locally on shingle or gravel banks by fresh water. They are widespread on coasts from spring to autumn and is the likeliest tern to be seen inland.

The nest is a mere scrape on the ground, in shingle or dry earth. In colonies near water. two to four eggs are laid and they have one brood.  The eggs may be encountered from May until June.The eggs are pear shaped and have some shade of buff in the ground colour, spotted or blotched with black, the distribution as well as the size of the spots varying somewhat.

When disturbed terns are very noisy and will mob any intruder with intent, so much so that other birds such as gulls and even partridges are killed by them. 

The Arctic Tern Sterna paradisaea.

Sterna paradisaea is a close relative of the common tern. This species is 33-39cm { 13-15 inches} long with a wingspan of 76-85 cm {26-30 inches}. they are mainly grey and white. In summer most have under parts so much darker grey that there is little or no contrast with the upper parts. The cheeks show as a white streak between the black crown and grey neck. The bill is blood red or coral red in summer, they are blackish in winter. In the intermediate stages, the base is red and tip black. The legs are coral red in summer blackish in winter.

This species also nests in colonies but rarely seen in land. It sometimes breeds along side the common tern.The general habits of the two species is much the same, but always builds near water and seems to dispense with any lining to the nest scrape. It is also a fierce bird in protection of its eggs and young and is more likely to strike home during an attack.

The eggs are exceedingly like those of the common tern, but average rather longer in shape, more strikingly spotted, and more olive brown in the tint of the ground colour. Two make up the usual set and June is the time they are commonly found. 

Arctic tern at nest

Photograph courtesy of Donna Dewhurst.

Arctic tern -Kirk Rodgers.

Other terns that may be seen around the coasts of the UK -- Least tern in flight

Photograph - Steve Hillebrand

 Top-Roseate terns.  Middle-Sandwhich terns Bottom -Caspian tern

Roseate terns-Photograph -Amanda Boyd. Sandwhich terns-Donna A Dewhurst. Caspian tern -Dave Herr.

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