NATURAL SELECTION AS APPLIED TO BIRDS 325 



forcibly from the rush and perched him on my hand, upon 

 which he ilew only fifty or sixty yards off, and dropped into 

 the dry grass. Here he again put into practice the same in- 

 stinct so ably that I groped about for ten or twelve minutes 

 before refinding him. . . ." Among a great number of desert 

 birds, and birds which haunt heaths and sandy plains, the 

 coloration harmonises remarkably, as we have already seen, 

 with the surrounding earth. And such birds, when threatened 

 by danger, endeavour to escape by flattening themselves out, 

 or lying prone upon the ground, and remaining there perfectly 

 motionless for some considerable time. The Norfolk Plover 

 and the Courser well illustrate this. The hen Pheasant, and 

 Partridge, and the Snipe and Woodcock are further illustrations 

 thereof, and such instances might be enormously extended. 

 Even birds of striking coloration, such as the Hoopoe, contrive 

 to mask their presence when threatened. The Hoopoe, at such 

 times, throws itself flat upon the ground, and simultaneously 

 spreads out the wings. As a consequence, it looks so little like 

 a living animal that it secures escape where escape seems im- 

 possible. But there are dozens of similar cases. 



Instances of anticryptic coloration are hard to find among 

 birds. They are developed, as we have already remarked, by 

 predatory species, and for the purpose of enabling their pos- 

 sessors to approach their victims unawares. The best, and 

 perhaps the only clear case, is that of the Snow Owl, which, 

 from its white plumage, is enabled to creep up unawares upon 

 its unsuspecting prey, which is also commonly coloured white, 

 it must be remarked — such as Hares and Ptarmigan and 

 Willow-grouse. 



It must be pointed out, however, that the interpretation 

 which has been placed on the significance of the winter 

 whitening of Ptarmigan, Willow-grouse and Arctic Hares has 

 been much challenged. And among these objectors are to be 

 reckoned naturalists of wide experience in the field, and their 

 dissent is based on observations which demand more attention 

 than they have yet received. 



Undoubtedly the most serious of the arguments which 

 they have brought forward with regard to this particular 

 coloration, is that the animals in question do not, as has been 

 assumed, pass the winter on the surface of the snow, but in 



