332 THE INDO-PACIFIC AND ITS SHORES 



Gannets and Various gannets, such as Sula cyanops, S. abbotti, S. sula, and 



Terns. $ piscatrix, congregate in thousands during the breeding-season on 



the tropical islands of the area under consideration, but as they belong to the same 



genus as the European species, they require but brief mention in this place. 



How they are robbed by frigate-birds is referred to in the preceding paragraph, 



and it will suffice to add that while one of the species, S. sula, visiting Christmas 



Island nests on the ground or on cliffs in much the same fashion as its European 



relative, the other two, S. abbotti and S. piscatrix, make nests of twigs on tall trees. 



To sailors the tropical species of gannets are invariably known as " boobies." 



Certain species of terns, such as the sooty tern {Sterna fuliginosa), are likewise 



some of the birds most numerously represented on the islands and coasts of the 



Indo-Pacific. The species just named has a very wide distribution, ranging over the 



greater portion of the tropical and subtropical oceans with the exception of the 



American side of the Pacific. On the Island of Ascension, for example, these birds 



collect in such enormous numbers as actually to darken the sky when on the wing, 



and equally large numbers collect on Raine and Laysan Islands, although they do 



not appear to visit Christmas Island. 



On still, warm days, mostly about noon, the terns of this species breeding on 



Laysan may be observed to rise from the water in a fan-like flock to a considerable 



height. In spite of the apparent want of order in which the thousands of birds 



move on the wing, the cylindrical shape of the flock is maintained as it rises and 



falls. These movements seem to have an attractive influence on other species, 



since tropic-birds, gannets, albatroses, and frigate-birds, although at other times on 



anything but good terms with the terns, gradually join the assemblage and take 



part in the evolutions. During the breeding-season sooty terns fly landwards from 



the sea punctually between three and four in the afternoon with their crops filled 



with food for their young, which are taken down to the water by their parents 



daily as soon as fledged. Flying a short distance ahead, the female bird encourages 



or cautions them by her call, which sounds like the words " wide-awake," and is 



uttered with varied modulations of tone, and answered by the feeble " peep-peep " 



of the young. 



Allied to the terns, and belonging to the family Sternidce, is 

 Noddies. 



the group of tropical sea-birds to which, in allusion to their apparent 



stupidity and indifference to man, sailors have given the name of " noddies." 



These birds, which are characterised by their graduated tails, are most numerously 



represented in the Southern Hemisphere, where they are met with further from 



land than the true terns. One of the best-known representatives of the group is 



Anous stolidus, a sooty brown bird, with a grey head, black lores and beak, a 



whitish forehead, and brown feet. 



The fairy tern (Gygis alba), typifying yet another group, with 



three species, ranges over the southern oceans as far west as the 



Seychelles. This beautiful white bird is distinguished by the long, forked tail, the 



slightly upward bend of the beak, and the deeply emarginate webs of the toes. 



The single egg is deposited on bare sand, on the crust of salt near the margins of 



lagoons, or on bare rocks and cliffs close to the surf, or even occasionally on a 



forked branch. However awkwardly the egg may be placed, the bird will always 



