98 THE STORY OF THE BIRDS 



pigment, named by Professor Church " turacin," 

 and containing copper, soluble in water. This 

 colour is not unfrequently washed out if the 

 birds get their plumage wet, although it is sub- 

 sequently regained. 



The Cuckoos are distinguished by their com- 

 plete zygodactyle feet, and the absence of an 

 aftershaft to the contour feathers. The bill is 

 very variable in shape, nearly straight, curved, 

 arched, and in some few species exceptionally 

 large, or the upper mandible laterally com- 

 pressed into a mere plate. The wings are long 

 and pointed in the migratory species, more 

 rounded and concave in sedentary forms. The 

 tail, consisting of ten feathers (except in a single 

 sub-family, the Crotophaginae, where they are 

 only eight), is usually long, and either square, 

 fan-like or wedge-shaped. In some species the 

 upper tail coverts are half or quite as long as the 

 rectrices or tail-feathers. Some of the Cuckoos 

 are remarkable for their occipital crests, whilst 

 bifurcate feathers are frequent on the head and 

 neck. Some of the species are remarkably social, 

 others are as solitary in their habits. There are 

 arboreal and terrestrial species. Their food 

 consists of insects, larvae, reptiles, small animals 

 and birds, and in some cases seeds and berries 



