60 



SAVAGE SUDAN 



appearances of each are roughly shown in various diagrams 

 passim. Then take the fish-catching birds. Both darter 

 and cormorant capture their prey by fair chase under 

 water ; yet while one needs a strongly hooked beak, the 

 other dispenses with a hook but substitutes, in lieu thereof, 

 serrated mandibles. The herons are no less adepts but 

 need neither hook nor serration, though the rim is 

 slightly roughened. The question, however, is too big 

 to discuss here mergansers, grebes, gannets would all 

 have to be called as witnesses. All are built for a similar 



object ; yet, while all differ in 

 armament and equipment, 

 all equally succeed. It may 

 be held there are causes 

 assignable to every effect, a 

 reason for each fact ; if so, 

 in these cases the predispos- 

 ing factors lie far beyond the 

 range of our finite vision. 



Of the egrets I write in 

 diary: "The great white 

 egret of Nile is bigger than 

 any seen in Spain. It is 

 Herodias alba, and has a 

 yellow beak and black legs. The middle-sized egret 

 (//. brachyrhynchus] has black beak and yellow legs, 

 while in the little egret (H. garzetta) both beak and 

 legs are black. Why? Their style of fishing differs 

 from that of the herons. The latter stand statuesque 

 as though carved in granite, awaiting the approach of 

 prey, and make but a single spear-thrust. Patience is 

 their policy ; whereas the egrets are ever hunting actively 

 about the shallows, and frequently put in a short run, 

 followed by several consecutive strokes, quick as lightning. 

 "A flight of weaver-finches sweep down to the river's 

 edge for a drink, alighting close by a big white egret. 

 Him the thirsty crowd suspect not. Suddenly, with three 



GLOSSY IBIS. 



