262 



RRPTJLES AND BIRDS. 



The appearance of these birds announces, as we have said, that 

 the navigators have entered the torrid zone, as they rarely go beyond 

 the limits of this region. It sometimes, however, pushes out to sea 

 to a distance of a hundred leagues. When they are fatigued, aided 

 by their large webbed feet, they rest upon the waves. Like many 

 other ocean birds, their peculiar organisation prevents them settling 

 on the ground from choice. They, therefore, skim continually over 

 the surface, on which they obtain their food, which consists of fish 

 and molluscs. To enjoy a state of quiescence, the immense spread 



Fig. 96. Tropic Bird. 



of their wings forces them to choose an elevated perch, such as the 

 top of a tree or the summit of a rock. When worn-out by fatigue, if 

 they settle on the water, they are forced to wait until they are lifted 

 on the crest of a wave before they can again take flight. Their mode 

 of flying is peculiar, for they communicate to their wings a kind of 

 quivering motion. 



These birds seek remote and solitary islands for the purpose of 

 breeding. They build their nests in trees, or in the clefts of rocks, 

 but always in some position difficult of access. They lay two or 

 three eggs. The young ones, when just hatched, owing to their 

 dazzling-coloured down, bear a considerable resemblance to powder- 

 puffs. 



