326 BIRD BEHAVIOUR 



It is interesting to note that the terrestrial forms 

 of some of these families, the Cereopsis among 

 the Geese, and the Land- Rail and Wekas among 

 the Rails, nevertheless still keep up the wholesale 

 moult of their, presumably, marsh-living ancestors, 

 and that the Ratite birds do not cast all their quills 

 at once, though there is a strong tendency to 

 wholesale moulting whenever possible ; thus the 

 ornamental plumage of the Gold Pheasant and 

 Peacock is shed very rapidly, as are the great show- 

 quills of the Argus. The Penguins also moult 

 very quickly, throwing off their feathers in masses, 

 and as they do not go into the water till clean- 

 moulted, have to fast for a period of several 

 weeks. 



The colour of the beak and sometimes the feet 

 changes in many cases according to season ; thus 

 the cock Chaffinch's bill is flesh-colour in winter, 

 blue-grey in summer ; and the Starling's beak 

 changes from black in winter to yellow in summer, 

 and its legs from dull brown to fleshy red. The 

 legs of the breeding Night-Heron (Nycticorax 

 griseus) also change from yellow to salmon at the 

 breeding season, and in some races of the Great 

 Egret (Herodias) the bill and face change, from 

 yellow, to black in the former and green in the 

 latter. Drakes when assuming the female-like 

 plumage they bear for a time after breeding may 

 or may not change the colour of their bills ; there 

 is no change in the Mallard or Pintail, but the 

 Gadwall and Shoveller assume the female colora- 



