BIRD LIVERIES AND THEIR MEANING. 29 



males are more beautifully coloured than the 

 females, or rather, of how the males have ac- 

 quired their superior beauty we shall consider in 

 a later chapter. 



We mentioned just now, that the plumage of 

 the females was often of a sombre hue when that 

 of the males was of a brilliant colouration : and 

 remarked that this was for protective purposes. 

 In the cases in point, however, this need for 

 protection was only partial and requisite only 

 during the breeding season. In some cases, how- 

 ever, as of desert-dwelling species the tone of 

 colouration both of males and females is that of 

 the surrounding country. Shelter being difficult, 

 the birds are consequently always exposed to 

 attack, and hence both sexes have come to assume 

 a tint precisely similar to that of the sand and 

 rocks by which they are at all times surrounded. 

 From this fact they can more easily escape ob- 

 servation from their enemies. Desert wheat-ears, 

 sand-grouse, and coursers, are the best known 

 examples of this kind of protective colouration 

 as it is called. 



Sometimes we have a seasonal protective 

 colouration. The British ptarmigan affords us 

 a splendid illustration of this kind. In the 

 summer and autumn both male and female are 

 clothed in a dark plumage, a mixture of dark 

 brown, black, buff and grey — according to the 

 SOX and time of the year. In winter, both don 

 a white dress, so as, apparently, to harmonise 

 with the snow-clad hills amongst which they 

 roam, again to render themselves less conspicuous 

 and so to escape from their ever present enemies 



