326 BIRD BEHAVIOUR 



It is mterestiiig to note that the terrestrial forms 

 of some of these famiKes, the Cereopsis among 

 the Geese, and the Land- Rail and Wekas amoajg 

 the Rails, nevertheless still keep up the wholesale 

 moult of their, presumably, marsh-living ancestors, 

 and that the Ratite birds do not cast all thfeir quills 

 at once, though there is a stroag tendency to 

 wholesale moulting whenever possible ; thus the 

 ornamental plumage of the Gold Pheasant and 

 Peacock is shed very rapi'dly, 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 iwto the water till clean- 

 moulted, have to fast for a period of several 

 weeks. 



The colour of the beak and sometimes the fefet 

 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 wiiiter to yellow in summer, 

 and its legs from dull brbwn to fleshy red. The 

 legs of the breeding Night-Heron {Ny^ticerax 

 griseus) also change from yellow to salmon at the 

 breeding season, and in some races of the Great 

 Egret {Herodia's) the bill attd 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 attd Shoveller assume the female colora- 



