ORNITHOLOGICAL OBSERVATION IN ICELAND. 297 



the coloration of any one species is concerned, is to use a very 

 double-edged weapon indeed. On the other hand, if it has really 

 been evolved as a more effective substitute for an eye not in keep- 

 ing with the rest of the face, this is an interesting circumstance, 

 as showing how active a factor the taste of a female bird is. But 

 this is involved in the doctrine of sexual selection, and surely it 

 is no more strange that variations which have ultimately pro- 

 duced a sort of mock eye should have been noticed and appre- 

 ciated, than those should have been which have made a real one 

 as yellow as is that of the Golden-eye, or as brightly ruby- 

 coloured as is that of the Sclavonian Grebe. 



As for any effect being produced by the pantomime plumage 

 of the male Harlequin Duck, by virtue of which it could be 

 supposed to add one more to the many pungent illustrations of 

 concealing coloration, which now usurp the province of sexual 

 selection, I can only, after seeing the bird at large, protest 

 against any such idea. No doubt it can hide itself, and, by 

 keeping perfectly still, it might not be noticed, even by the keen- 

 eyed Hawk or Falcon. But that only shows the protective 

 powers of immobility, and how effective this agency is (though 

 so little, comparatively, is said about it) as an antidote even to 

 conspicuous coloration, and, in a certain degree, even to scent.* 

 It is, in fact, that which has probably made the first of 

 these, and, along with it, selection, possible — for the bird, or 

 other animal, that, being hard pressed by enemies, yet keeps 

 constantly in motion, will fare badly, however it may blend and 

 harmonise. 



June 11th. — I go to bed about 8, and get up again, at 31, 

 with the idea of watching through the night. As I come out of 

 my tent, there on the water, just in front of me, is the Great 

 Northern Diver again, accompanied, this time, by its mate, 

 which I take to be the female, for there is a noticeable difference 

 in size between the two, and in the larger, rightly or wrongly, I 

 seem to recognize the one I have seen before. These birds are 

 not at all afraid of me. They dive and swim about together, 

 often side by side, or float, facing each other, in attached and 

 friendly fashion, sometimes quite near. Both are very vocal, 



* The scent, through keeping still, will be less left about, thus lessening 

 the chances of its being struck. 



Zool. ilh ser. vol. XVII., August, 1913. 2 a 



