PRELIMINARY CLASSIFIED NOTES 57 



consisting mainly of immature birds in small parties. At that season the birds are 

 more widespread, occurring irregularly in Ireland, and they also penetrate some 

 distance inland along the rivers. A few may linger as late as November in the 

 south-west (cf. Saunders, III. Man. B. B., 2nd ed., 1899, p. 633 ; and Ticehurst, 

 B. of Kent, 1909, p. 490). [A. L. T.j 



4. Nest and Eggs. Although no longer one of our breeding species, the 

 black-tern continues to visit us occasionally in the summer months. Its nest 

 consists merely of a few water-weeds and decaying vegetable matter, built up till 

 just above the level of the shallow water, and partly supported by rushes and other 

 growing water-plants. (PI. XLII.) The materials are provided by both sexes. The 

 eggs are usually 3 in number, occasionally only 2, and are olive-green or ochreous 

 in ground-colour, spotted and blotched with irregular markings of very dark sepia, 

 almost black, and purplish grey underlying shellmarks. (PI. H.) Average size of 

 100 eggs, 1'35 x *97 in. [34'5 x 24'8 mm.]. The nests are generally to be met with in 

 colonies of varying size, and are found in shallow lakes or marshes overgrown with 

 water-lilies, rushes, and other forms of aquatic vegetation. The usual breeding 

 time is from about May 20 to the first week of June in Central Europe, but in South 

 Spain eggs may be found by the middle of May. Naumann states that both sexes 

 incubate in turn, but the hen alone at night, and that the incubation period lasts 

 14-16 days. 1 Only one brood is normally reared in the season, but if the first 

 clutch is taken, another is deposited soon afterwards. [F. c. E. J.] 



5. Food. Chiefly aquatic insects and their larvae, also land insects, earth- 

 worms, and occasionally, according to Naumann, little frogs, spawn, and small 

 fish. [F. B. K.] 



COM! 3VI O N - T E R N [Sterna hirundo Linnaeus ; Sterna fluvidtilis Naumann. 

 Sea-swallow, sparling, skrike (generic), kip (Kent). French, hirondelle de 

 mer, Pierre-Garin ; German, Fluss-Seeschwalbe ; Italian, rondine di mare']. 



I. Description. The common-tern is to be distinguished by the orange-red 

 colour of the beak, which is black-tipped, the pale vinaceous grey under parts, the 

 broad band of dark grey which runs along the inner side of the white shaft of the 

 outer primaries (see Arctic-Tern, p. 61), and the length of the tarso-metatarsus, 

 which is longer than the middle toe minus the claw. (See also p. 76.) The 

 sexes are alike, and there is an incomplete winter, as distinct from the summer, 



1 See, however, notes on the incubation period under sandwich and little-tern. 

 VOL. III. H 



