Eyes of Birds. 35 



of the kea are now numbered in New Zealand. But 

 from the purely psychological point of view the case is 

 an interesting one, as being the best recorded instance 

 of the growth of a new and complex instinct actually 

 under the eyes of human observers.'' 



So fruit-eating, in the sense I mean here, is entirely 

 an acquired taste, and more and more the birds learn 

 it. The sparrow and the bullfinch, no doubt at first 

 cleared the gooseberry bushes from small grubs or 

 insects in the spring, but they could not help now and 

 then getting a taste of the eye-buds as they picked the 

 insects out, and came to form a taste for the buds 

 themselves, which now they so ravenously devour, that 

 in some parts covering the bushes with black threads, 

 crossed from point to point, is the only protection. 

 The birds do not see these till they dash against them 

 and are frightened. So I believe that the starlings 

 have become corrupted, or are in gradual process of 

 being so. 



In a later page we shall see how the rook bears the 

 blame of grain-eating when he only picks out, at a 

 certain stage, the grains which have become the dwell- 

 ing-places of the intrusive wire- worm; but it is possible 

 enough that if insect-food became very scarce through 

 one reason or another, the rook might resort to grain- 

 eating alone. 



And this suggests a word or two about the eyes of 

 birds, which are indeed wonderful in their adaptation 

 to be used alternately as a telescope and a microscope. 

 We speak of a birds-eye view, and that is expressive 

 enough, but it hints only at one-half the wonder. The 

 birds can see far, but they can also see near. In some 

 cases the focal distance is remarkably short, being no 

 more than the length of the bird's bill, whereas in the 



