

THE GREEN WOODPECKER 77 



hurtful to vegetation, better deserves protection at 

 the hand of man. Luckily, all the woodpeckers are 

 very wary in their habits, seldom offering a chance 

 shot to the mischievous hedgepopper, and requiring 

 to be approached stealthily, even by the friendly 

 observer of its movements. It is worth some pains 

 to watch the yaffle at work upon a tree. Beginning 

 at the root, it raps incessantly as it works up the 

 stem, probably with the double purpose of disturb- 

 ing any lurking insects and of detecting any un- 

 sound wood where fat grubs may be harboured. As 

 soon as the game is afoot, the tongue of the bird 

 comes into play a most serviceable instrument for 

 picking up creeping things. The tip is horny and 

 armed with a few bristles ; the bone of the tongue 

 is prolonged backwards in two branches, reaching 

 round the back and over the top of the head, and 

 meeting again in the cavity of the right nostril, 

 where they are fixed. Inside the bow thus formed 

 runs a strip of muscle, which, when it is contracted, 

 bends the bow and extrudes the tongue. Then, 

 beneath each ear is a gland discharging a glutinous 

 secretion into the trough of the lower mandible, 

 where the tongue lies when at rest, so that the bird 

 is able to catch the smallest creeping thing. 



