The Common Tern or Sea-swallow (Sterna hirundo), Fig. 51, is a member of the Natatorial or Swimming Birds of the Laridae or Gull family and sub-family Sterninae, arriving on British shores in May and leaving them in September. Its average length is 15 in., the long-forked tail forming a considerable part of this measurement. The head and neck are black and the upper part generally ashy-grey, whilst the lower parts are white, and the legs, feet and bill red. It is very active, seemingly in ceaseless flight, and darting down upon small fishes, which constitute its food. Its cry is noisy and jarring. The nest is made on the sand or rock above high-water mark, and contains two or three eggs, on which the female usually sits by night.

The Common Tern or Sea swallow.

Fig. 51. - The Common Tern or Sea-swallow.

As evidence of the destructive nature of the Common Tern, it is noteworthy that the East Suffolk County Council was in 1906 petitioned by 100 fishermen of Aldeburgh to rescind the order prohibiting the taking of the eggs of the common tern, as during the last ten years the birds had greatly increased, and the smelt fishing industry had been nearly destroyed. It was estimated that there were 40,000 birds in the district, and one bird alone had been seen to take thirty to forty young fry in an hour. The council decided to allow the order to expire in January, 1907.