5IO 



GULL TRIBE. 



the marsh-terns are specially distinguished by the rounded or slightly pointed tail- 

 feathers, the short tail, which is less than half the length of the wing, the small 

 beak, with the culmen less than twice the length of the metatai-sus, and the feeble 

 feet, in which the w^ebs are considerably indented between the toea All these 

 terns nest in marshes, either on tussocks of grass, or among floating vegetation. 

 The best known of the British species is the black tern {H. nigra), in which the 

 under-parts in the adult summer plumage are dark leaden grey ; the upper tail- 

 coverts and tail being grey, the beak black, the chin and sides of the face like the 

 under-parts, the crown nearly black, and the under wing-coverts pale grey. On 

 the other hand, the whiskered tern (H. hyhrida), which is but an occasional 

 straggler to Britain from the south, has the beak blood-red, the chin and sides of 

 the face pure white, the throat and breast grey, passing into blackish grey on the 



abdomen, and the 

 under wing- 

 coverts white. 

 Abundant in 

 Southern Europe, 

 this tern ranges 

 over a large part 

 of Africa and 

 most of Asia. 

 The beautiful 

 white - winged 

 black tern {H. 

 ^cucop<cra),which 



is likewise but a rare visitor to the British Isles, differs from both the preceding 

 in that the upper tail-coverts and tail are white in the adult summer-plumage, the 

 under-parts being black as far as the vent, and the under wing-coverts of the 

 same hue, while the beak is dull red. Rare in Northern Europe, this species is 

 more common in the south and east, whence its range extends over the greater 

 portion of Europe. Mr. Saunders writes that " the black tern breeds in colonies, 

 the nest being situated in marshes, and formed of decayed pieces of Equisetum and 

 other plants, or heaps of wrack, which rise and fall with the tide ; sometimes they 

 are placed on the firmer hummocks of bog in the middle of shallow parts. The 

 eggs are three in number, of various shades of ochreous clay, olive-brown, or olive- 

 green, blotched with dark brown, especially at the larger end. The food of this 

 tern consists chiefly of beetles and dragon-flies, with some small fish ; it is also 

 very partial to leeches." 



The true terns, of which the common tern (Sterna fiuviatilis) is the 

 typical form, differ from the marsh-terns and their allies by the distinctly 

 pointed outer tail-feathers ; while they are further characterised by the shortness 

 of the metatarsus, the moderately elongated tail, and the compressed and slender 

 beak. With two exceptions, these terns have the crown of the head black ; 

 while, as a rule, the under-parts are white or grey, although in the Oriental 

 black-bellied tern {S. tnelanogaater) they are black. The common species, as well 

 as the Arctic {S. macrura), roseate (S. dougalli), and Sandwich tern (S. cantiana) 



HEAD OF BBOAO-BILLED TERN. 



(From Saunders, Proc. Zool. Soc., 1876.) 



