84 A BOOK OF BIRDS 



tail, the outer feathers of which, like those of the Swallows, are much 

 longer than the inner. Hence the Terns are often known as 

 *' Sea-swallows." 



The Little Tern (Plate XVI. fig. 6) in its general appearance 

 resembles the Common Tern, from which, however, it may readily 

 be distinguished, since it does not exceed 9^ inches in length, and 

 has the beak orange-yellow and tipped with black. In North America 

 the Little Tern is represented by a very closely related species, the 

 Antilles Tern ; the latter, however, may be distinguished by having 

 the rump grey, and very little black on the back. 



This is the smallest of the British Terns, and makes its appear- 

 ance among us during the month of May, departing again in 

 September and October. 



The Sandwich Tern (Plate XVI. fig. 5) derives its name from 

 the place where it was first observed — Sandwich, in Kent — so far 

 back as 1784. It is a regular visitor to Great Britain, arriving during 

 March and April. Like the two species just described, the crown 

 of the head in summer is black, while the beak is black, and yellow 

 at the tip. The back, as in the other Terns and many of the Gulls, 

 is of a beautiful pearl-grey, the under parts being white, but tinged 

 with a most wonderful salmon-pink colour, which fades rapidly 

 after death. The legs and feet are black ; and in this it differs 

 again from the Terns just described. 



Finally, we come to a group of very curious Gulls known as 

 Skuas. These differ from the typical Gulls and Terns not only ana- 

 tomically, and in their more sombre coloration, but also in their 

 peculiar habits, which may be described as semi-parasitic. And this 

 because these birds contrive to gain most of their food by chasing 

 Gulls which have recently fed, and compelling them to disgorge their 

 captures to avoid further buffeting. So expert a highwayman has 

 the Skua become, that he will catch the fish dropped by his victim 

 before it can reach the sea again. 



Skuas also devour the eggs and young of any other birds which 

 may have the misfortune to be breeding in their neighbourhood. 



The nestlings of the various species of Skuas differ from those 

 of Gulls and Terns in being dark, and whole coloured, not grey and 

 mottled with black as in Gulls and Terns. 



