46 THE WORLD'S BIRDS. 



NEST. A collection of sea-weed, etc., placed on rocks, 

 trees, or bushes. 



EGGS. One or two ; with a coat of chalky matter 

 over a blue shell. 



INCUBATION. About six weeks (in the Common 

 Gannet). 



FOOD. Fish and other marine animals ; some species 

 plunge for this from a height like our Gannet, 

 others fly low and sweep down on it, like the 

 Booby. 



GAIT. A slow and awkward walk ; they carry the body 

 horizontal, not erect like Cormorants ; they swim 

 high and lightly. The tropical species perch on 

 trees. 



FLIGHT. Very powerful, performed by alternate flap- 

 pings and sailings ; the neck is extended in front and 

 the feet carried under the tail. 



NOTE. A harsh croak or cackle ; but they are not con- 

 stantly noisy like gulls. 



DISPOSITION AND HABITS. Although sociable, they 

 are somewhat surly in temper ; they are purely 

 marine, never coming inland voluntarily. 



ECONOMIC QUALITIES. The young of the Common 

 Gannet are used as food, and several of the tropical 

 species are valuable guano -producers. 



CAPTIVITY. Gannets do not do well as a rule in this 

 condition, probably because they take hardly 

 any exercise ; but Booth was very successful 

 in keeping the common European species many 

 years ago, and they bred and reared young. 



DISTRIBUTION AND IMPORTANT SPECIES. About eight 

 kinds of Gannets are known, mostly inhabiting the 

 warmer seas ; our only British species (Sula 

 bassana) is widely distributed over the northern 

 seas and is the only kind in the north. The most 

 familiar species in tropical seas is the Common 

 Booby (Sula sula), about as big as a wild duck, 



