WINTER DRESS 305 



markings is supplied by the small black spots or patches in 

 the white coats of all this group of Arctic birds and beasts. 

 The ermine has its black tail-tuft, the mountain hare its 

 black ear-tips, and the ptarmigan its black tail-feathers and 

 eye-stripe. In every case there is some definite mark of 

 contrast to the general design. Patches of this kind are 

 sometimes explained as recognition marks, enabling one 

 bird or animal of a brood to catch sight of its companion 

 and follow it when hastily changing ground. But if it served 

 to make its wearer more conspicuous, it would be more likely 

 to endanger it than assist it. It seems more likely that the 

 real effect of these contrasted markings is to conceal the 

 whole outline of the bird or animal by concentrating the 

 attention upon one particular spot. In looking at a bird 

 sitting in an open nest, such as a nightjar or pheasant, the 

 eye is often caught by some particular spot or bar in the 

 plumage without realising that it is part of a living creature. 

 It looks like a stick or shadow or dry leaf; and when the 

 attention is localised in this way, it is less likely to recognise 

 the bird's complete outline. The same effect can often be 

 seen in a photograph. It is the same with large and 

 boldly contrasted markings as with the mottled plumage of 

 the pheasant. A sheldrake is an extremely conspicuous 

 bird as one sees it on an aviary pond ; but the eye can 

 easily miss it a hundred and fifty yards away on the mud- 

 banks or the water. The white parts in its plumage blend 

 with the reflected light on the mud or water, and the darker 

 patches are dispersed and suggest nothing like a bird. The 

 black and white markings of the ptarmigan and its com- 

 panions of the snow fields probably have a similar effect. 

 In most cases the small black marks are situated at or near 

 some extremity ; when they catch an enemy's eye on the 

 snow they would tend to prevent it from getting a general 



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