THE WORLD'S BIRDS. 171 



Tropic-Birds {Phaethontidce). 



Diagnosis. — Long-winged sea-fowl, with long pointed 

 tails, and all the toes united by a web, and non-hooked 

 bill. 



Size. — About that of a crow or small gull. 



Form. — Bill nearly straight, upper outline curved, 

 horny covering uniform, with distinct slit -like 

 nostrils and corner of mouth reaching below eye ; 

 feet small, with very short shanks and all toes 

 united by a web, the first very small and turned 

 inwards ; wings very long ; tail long and pointed, 

 the centre feathers especially long. Head large, 

 neck short. 



Plumage and Colouration. — Feathering satiny, 

 colouring mostly white or very pale ; no sexual 

 difference or seasonal change. Adults with central 

 tail feathers very long ; young with the upper 

 plumage black-barred. Bill red or yellow, eyes 

 and toes dark. 



Young. — Helpless and fed by parents ; clothed in very 

 full fluffy white down. 



Nest. — None, the birds breeding in an unlined hole in 

 a rock or tree. 



Egg. — One ; white, mottled with brown. 



Food. — Sea-fish, on which the birds swoop from the 

 air. 



Gait. — An awkward waddle ; they seldom need to 

 walk, but perch quietly when not flying ; they are 

 not often seen at rest even on the water. 



Flight. — With rapid continuous beats of the wings, 

 like a duck's. 



Note. — A harsh scream or prolonged whistle. 



Disposition and Habits. — They are brave birds, 

 resenting intrusion when nesting. They are 

 usuaUy seen well out at sea, generally singly or at 

 most in pairs, and almost always on the wing. 



