The family Laridae is composed of two chief groups, Larinae and Sterninae - the gulls and the terns, though two other subfamilies are frequently counted, the skuas (Stercorariinae), and that formed by the single genus Rhynchops, the skimmers; but there seems no strong reason why the former should not be referred to the Larinae and the latter to the Sterninae.
Setting aside those which are but occasional visitors to the British Islands, six species of terns may be regarded as indigenous, though of them one has ceased from ordinarily breeding in the United Kingdom, while a second has become so rare and regularly appears in so few places that mention of them must for prudence sake be avoided.
All around the coast the diminution in the numbers of the remaining species of terns is no less deplorable than demonstrable.
Terns are found all over the world, and among exotic forms may be particularly mentioned the various species of noddy.
Often confounded with these last are the two species called in books sooty terns (S.