CHAPTER XII 



THE COLOURS OF BIRDS 



General Characters of the Coloration of Birds — Sexual Colora- 

 tion — Distribution of Colour and Colour Variation — Food 

 and Colour — Pigments of Birds, their Characters and 

 Distribution — Pigments of Birds' Eggs — Markings of 

 Feathers. 



The colours of birds often rival or surpass those of 

 insects in brilliancy and variety, and have attracted 

 quite as much attention. Indeed, the greater size of 

 birds and their greater specialisation give to their 

 colouring a variety and a charm which many fail to 

 find in insects ; this widespread admiration has un- 

 fortunately been in many cases singularly fatal to 

 the birds. 



Birds resemble insects in displaying both types 

 of colour — the optical and the pigmental — to great 

 perfection ; but in marked contrast to the conditions 

 which prevail in the Lepidoptera, we find that the 

 bright pigments are usually lipochromes, never so 

 far as is known waste products of the uric acid 

 group, Further, although there are several instances 

 described of birds whose colours can be heightened 

 or altered by the employment of special kinds of 



