The Sooty Tern. 53 



that. The first appearance of these birds in 1877 was during the first week in 

 October, and they continued to arrive daily for about two months. Their annual 

 coming is said to be somewhat irregular, and they are stated to breed three times 

 in two years, concerning which Mr. Howard Saunders has kindly allowed me to 

 make the following extract from a letter to him from Mr. Unwin, dated September 

 5th, 1879. " The 'Wideawake' visits this island at, and remains for, very uncertain 

 intervals, not every eight months [as has been asserted] ; of this I am very certain 

 from nearly four years' experience. Were not their eggs used so largely for food 

 in this barren place, one could form some idea as to the length of time nature 

 intended them to remain. I may, of course, be miles out in my opinion ; • but I 

 fancy that, were it possible to take away the eggs immediately they are laid, the 

 birds would not leave for a very considerable period. Last year they remained 

 months longer than usual, owing to a very unusual downpour of rain, which flooded 

 their breeding ground and killed thousands of young birds. They left about May 

 and were back in August. It seems to me that no matter how often an egg is 

 taken, another is laid, and the old birds still persevere in trying to rear a young 

 one " 



" Each bird normally lays only one egg ; but when constantly plundered the 

 same bird lays several times ; and those who collect get, in a good morning's 

 work, about two hundred dozen eggs. This fairly shows the number of birds and 

 their closeness together. The eggs are said not to be so good as Plover's eggs, 

 having a slight fishy flavour." 



Mr. Bourne, who visited the island of Diego Garcia in 1885, writes that when 

 he arrived on September 15th, Terns "were breeding in countless numbers on 

 some of the less frequented parts of the island. The dark grey Terns \Sterna 

 bernsteini\ build rough nests composed of a heap of sticks and leaves piled up in 

 the forks of trees and bushes ; in each of these a single egg is laid, on which 

 the female sits. The black and white Terns \_S. fuliginosa\ lay a single egg on the 

 bare ground, which is apparently hatched by the heat of the sun, for I never saw 



one of these birds sitting As soon as the breeding season was over, the 



number of Terns diminished very considerably ; it seems that they assemble in 

 these remote islands for breeding, and fly off to continents and larger islands for 

 the remainder of the year." 



In full breeding plumage both sexes (which are similar at all corresponding 

 ages) have the centre of the forehead, with a stripe extending to over, but not 

 beyond, the eye, the sides of the head and neck, the chin, throat, breast, and 

 under surface of the wings, pure white ; under tail-coverts, abdomen and flanks, 

 greyish-white; the loral stripe, which quite encircles the eye, the head, and the 



Vo.L VI. T 



