The Sandwich Tern. 29 



they and their contents were so difficult to distinguish from the sand and fine 

 gravel, that my first discovery of the colony was to find that I had ' put my foot 

 in it.' " 



These terneries are often very large and the nests so close together that it is 

 very difficult to traverse them without stepping on the eggs. Close by may 

 often be found the nests of other species of Tern, of Gulls aud of other sorts 

 of water-fowl. 



The eggs vary in number from two to three : frequently only two, but never 

 more than three, are laid. They differ considerably in size, and are, as a rule, 

 conspicuously but very varyingly marked ; the ground colour being brownish-buff, 

 cream, or oil-green, blotched or spotted with dark brown and black, with other 

 spots, blotches and scrawls of a lighter shade, seen distinctly underlying the surface of 

 the shell. Their size is from 2 inches to 2 J in length, and about ij inch in diameter. 



Only one brood is raised in the }^ear. The length of incubation is about 

 three weeks, at the end of which — from the middle to the end of June — the little 

 downy chicks, pure white below, and buffy-grey mottled with greyish-black on 

 the back and upper side, break their prison walls. The chicks are all quite alike 

 despite the great variability of the eggs. 



Soon after the date of the commencement of incubation, the parent birds begin to 

 lose the black head, and at their autumn moult they assume their winter garb, 

 which differs from that of the summer, in having the feathers in the upper part 

 of the head white with only a median black patch ; those of the back of the head 

 bluish black with white margins ; a black spot in front of the eye, and the nape 

 streaked with black ; the roseate hue on the underside is slightly paler than in 

 summer. 



The young birds in their first plumage are constantly to be seen in company 

 with their parents throughout the remainder of the summer till about the end 

 of September or beginning of October, when all together they take their migratory 

 flight southwards. In the immature birds the bill is shorter than the head, is of 

 a horn colour and yellowish at the tip ; the feathers of the nape are oblong and 

 rounded, their garb differs from the winter attire of their parents in having the 

 forehead with small brownish-black touches ; the upper part of the head and nape 

 dull white, mottled with brownish -black and pale-reddish ; the fore part of the 

 back and shoulders and the rest of the upper parts as in the adult, but every- 

 where marked with reddish-brown barred with blackish-brown ; an ashy grey band 

 along the lesser wing coverts ; the quills dark grey edged and tipped with white ; 

 tail feathers white and tipped with dusky-white. The occipital crest appears only 

 after the first moult, that is in the second autumn of their age. 



Vol. VI. F 



