6 Evolution and Adaptation 



white coat in winter, and a brown coat in summer. The 

 white winter plumage renders the animal less conspicuous 

 against the background of snow, while in summer the 

 plumage is said to closely resemble the lichen-covered 

 ground on which the bird rests. The snowy owl is a north- 

 ern bird, whose color is supposed to make it less conspicuous, 

 and may serve either as a protection against enemies, or 

 may allow the owl to approach its prey unseen. It should 

 not pass unnoticed, however, that there are white birds in 

 other parts of the world, where their white color cannot be 

 of any use to them as a protection. The white cockatoos, 

 for example, are tropical birds, living amongst green foliage, 

 where their color must make them conspicuous, rather than 

 the reverse. 



The polar bear is the only member of the family that is 

 white, and while this can scarcely be said to protect it from 

 enemies, because it is improbable that it has anything to fear 

 from the other animals of the ice-fields, yet it may be claimed 

 that the color is an adaptation to allow the animal to ap- 

 proach unseen its prey. 



In the desert many animals are sand-colored, as seen for 

 instance in the tawny color of the lion, the giraffe, the 

 antelopes, and of many birds that live on or near the ground. 



It has been pointed out that in the tropics and temperate 

 zones there are many greenish and yellowish birds whose 

 colors harmonize with the green and yellow of the trees 

 amongst which they live ; but on the other hand we must 

 not forget that in all climes there are numbers of birds 

 brilliantly colored, and many of these do not appear to be 

 protected in any special way. The tanagers, humming-birds, 

 parrots, Chinese pheasants, birds of paradise, etc., are ex- 

 tremely conspicuous, and so far as we can see they must 

 be much exposed on account of the color of their plumage. 

 Whether, therefore, we are justified in picking out certain 

 cases as examples of adaptation, because of an agreement in 



