THROUGH THE YEAR 157 



of those could the brilliant, gem-like eye be of use 

 as a fascinator, even assuming the theory is good. 

 The pochard and the spoonbill do not live on food 

 that needs to be fascinated. The oyster-catcher 

 has a splendid crimson iris, but it could not have been 

 meant for fascination. Several of the herons have 

 remarkable eyes, mostly yellow, and I dare say 

 one in love with the theory might play with it 

 here. A heron will sometimes stand in the water 

 and stab with that terrible bill the fish that drift 

 past. Fish will be lured by powerful light focussed 

 on them after dark, and we know that the glitter 

 of a bright " fly " or spoon bait will draw them ; 

 but the heron's eye is well above the water, 

 and I doubt whether its glitter would be very 

 striking. 



Questions of light may often be the secret of the 

 varying irides of birds regulating the supply ol 

 light and serving to adapt it to the special needs of 

 the bird concerned. But another idea occurs to 

 one may not the gem-like eye in some birds be part 

 of the sexual finery ? The crimson eye set in 

 snow white, as with the spoonbill, is effective and 

 beautiful. Does the iris vary at all according to 

 the sex of the bird ? It often varies according to 

 the age of the bird ; some young birds do not get 

 their brilliant eyes till they have moulted and reached 

 a certain age. 



There is one strange thing about gem-like eyes 

 in birds which has never been discussed ; the colour 

 of the eye of one of the pochards will change colour 



