33 o THE INDO-PACIFIC AND ITS SHORES 



beak is red and the tail white, whereas in P. lepturus (or flavirostris) the beak 

 is yellow and the tail white, while in P. rubricauda the beak is red and the 

 feathers of the tail are crimson with black shafts and narrow webs. The most 

 beautiful species is, however, the yellow P. flavus of Christmas Island, in the Indian 

 Ocean. The white-tailed and the red-tailed species breed as far north as Laysan 

 Island, where there is a regular harvest of their eggs. On their way home from a 

 sea-trip to the shore of this or other islands, tropic-birds after fishing half the day 

 are often robbed of the results of their toil by predaceous frigate-birds and compelled 

 to return home empty. On arrival, after taking their places by their hungry off- 

 spring, the old birds will often administer severe blows to the latter should they 

 prove too importunate in their demands for the food which is not forthcoming. 

 On Christmas Island the red-tailed tropic-bird breeds almost exclusively in holes 

 in the cliffs, and is never seen flying about the trees. The yellow species, on the 

 other hand, deposits its single dark brown and mottled egg on the floor of a hollow 

 in a tree, with a mere apology for a nest. Although their flight is strong, these 

 beautiful birds, on account of the rapidity of the strokes of the wing, appear as if 

 labouring, and seldom sail with outstretched pinions. On hot days they may be 

 seen flying among or around the trees in pairs or in threes, continually uttering 

 their characteristic crackling cry, and occasionally hovering in front of holes in the 

 trunks or boughs as though in search of suitable nesting sites. The breeding- 

 season seems less definitely circumscribed than is the case among most birds, both eggs 

 and young having been taken on Christmas Island in August and September. 



Although, as indicated above, a deadly enemy, the greater 



Frigate-Birds. „ . , . _° ' , ., . . , , . J . , , J ' . . . & , , 



frigate-bird (jfregata aquila) is a near relative of the tropic-birds, but 

 represents, with the lesser species (F. ariel), a separate family, the Fregatidce ; the 

 former species ranging over the tropical and subtropical zones of the oceans of 

 both hemispheres, while the latter is restricted to the Indo-Pacific. From the 

 Phaethontidce frigate-birds are readily distinguishable at a glance by their colour 

 and shape, as well as by the forked tail ; another feature being the deep scalloping 

 of the webs of the toes, which are entire in the members of the other group. In 

 colour adult males of the larger species are almost wholly black above, but white 

 below, from the lower part of the breast ; in young birds, however, the head and 

 throat are rufous. In females the under-parts are white from the lower part of 

 the throat, and they also have a large white patch on the flanks. Early in January 

 the adult males begin to develop a great pouch of skin beneath the throat, which 

 is brilliant scarlet in colour and capable of being inflated till it becomes nearly 

 as large as the body. When taking to flight this bladder-like pouch, which only 

 persists in its fully developed condition during the breeding-season, is generally 

 allowed to collapse. For a great part of the year frigate-birds are denizens of the 

 open ocean, where they are surpassed in flight only by albatroses ; but during the 

 breeding-season they are compelled, like tropic-birds, to resort to remote oceanic 

 islands, where, as on Laysan and Christmas Islands, they congregate in enormous 

 flocks. The food taken by their own exertions consists of surface-swimming species — 

 as they never seem to dive — but much, if not the greater part, of their commissariat 

 is obtained by despoiling tropic-birds and gannets of their hard-earned prey. 

 When a gannet or a tropic-bird is overhauled by a frigate-bird, the marauder 



