THE PRIMEVAL FORESTS OF CENTRAL AFRICA. 219 



by fluttering their wings, and work in their material, singing all the 

 while. When one nest is built and finished inside, they proceed to 

 make a second and a third ; indeed, they may even pull a finished 

 work to pieces again to satisfy their love of building. Thus they go 

 on until the female, who has meanwhile been brooding, claims their 

 assistance in the rearing of the young ones. This activity animates 

 the whole colony, and the golden-yellow, mobile, active birds sitting 

 or hanging in the most varied positions, are an ornament to the tree 

 already decorated with their nests. 



On the mimosas, which are leafless just at the general brooding 

 time, the cow-weaver birds have erected structures very large for 

 the size of the birds, which are scarcely so large as our starlings. 

 Their nests are placed among the thickest branches at the top of 

 the thorny mimosas, and as they are made entirely of thorny twigs 

 on the outside, they have much the appearance of a scrubbing- 

 brush; they are often more than a yard long, half as high and 

 broad, and enclose roomy brooding-chambers entered by winding 

 tunnels corresponding to the size of the birds, and impassable to 

 other animals. On these trees, and about these nests, too, there is 

 much lively and noisy bustle. 



In the heart of the forest itself an attentive observer finds nests 

 everywhere, though it is often difficult to recognize them. Little 

 finches, for instance, build nests which are deceptively like heaps 

 of dried grass blown together by the wind, but inside there is a 

 soft, warm brooding-chamber lined with feathers; other birds choose 

 building materials the colour of which is deceptively like that of the 

 surroundings, while others do not build at all, but lay their earth- 

 coloured eggs on the bare ground. Every cavity in the trees is now 

 inhabited, and woodpeckers, barbets, and parrots are constantly at 

 work making new chambers, or widening and adapting already 

 existing cavities into brooding-holes, while the hornbills, on the 

 other hand, busy themselves plastering up the too-wide entrances. 

 The last-named birds are specially distinctive in their brooding 

 habits, and deserve to be mentioned first. 



When the hornbill by ardent wooing has won a mate, he helps her 

 to seek out a suitable hole to serve as a nest. This found, he labours 



