THE WOODPECKER'S TOOLS: HIS BILL 73 



When he is digging his house the woodpecker 

 use his bill as a pick-axe. When he is digging for 

 grubs he uses it as a drill. Now some species 

 drill very little and some a great deal, accord- 

 ing to the number of grubs they feed on ; but 

 all dig holes to nest in, — that is, all use their 

 bills as picks but only a few employ them as 

 drills. The flickers, for example, seldom drill 

 for grubs, their food being picked up on the sur- 

 face or dug from the earth ; yet they excavate 

 the deepest, roomiest holes made by any wood- 

 peckers of their size; they use their bills effec- 

 tively as pick-axes, but seldom, very seldom, as 

 drills. And what do we find ? No drill-point — 

 not a truncate, compressed bill fit for drilling, 

 but a sharper, pointed, rounded, curving bill. 

 Notice the ordinary pick-axe and see how much 

 nearer the flicker's bill than the logcock's or the 

 ivory-billed woodpecker's it is. Why is a flicker's 

 biU better for being curved also ? Why do the 

 drilling woodpeckers have a perfectly straight 

 bill? We should find by studying the birds 

 and their food that there is a direct relation 

 between the shape of the bill and the amount of 

 drilling a woodpecker does ; that the grub-eating 

 or drilling woodpeckers have a straight bill, for 

 working in small deep holes, while the flickers 

 have a curved bill for prying out chips. And 



