134 SOME RYOID HINTS. 



of tympanum for conducting vibrations to the 

 auditory nerves. 



The upper mandible of the woodpecker is 

 longer than the lower, and so it receives the 

 force of every blow made in pecking hard 

 wood. But this mandible is not movable. 



Now, if with a good opera-glass you will 

 carefully watch a hairy woodpecker when it 

 is trying to locate a wood- worm in a dead 

 limb, you will soon note that by marvelous 

 slight he first strikes the hard outer crust of 

 the wood a smart blow or two, making a dent 

 therein. Then into this dent he thrusts his 

 upper mandible, and allows his lower one's 

 point to rest against the wood ; at the same 

 time his tongue is drawn in to the utmost, and 

 the whole attitude of the bird is a listening 

 one. It is a swift movement, and will not be 

 noticed except by the most careful observer. 

 Now when the bird's tongue is drawn far in, 

 it rests between the prongs of the lower mnr- 

 dible, and, j:)ressing upon them, forms a per- 

 fect connection for receiving the vibrations 

 imparted thereto. 



I was at first of the opinion that in the 

 listening attitude Picus thrust his tongue 

 against the wood, but this was error, as I soon 

 discovered. 



III. 



Turning from tlie true woodpecker to the 

 modified species Melanerpes erythroceplialus^ 

 we find some curious facts. 



The hairy woodpecker {Picus villosus) is a 

 much smaller bird than the red-headed spe- 

 cies {Melanerpes erythrocephalus) , yet the 

 former has the more powerfully fluted bill 

 and a brain thrown much farther back in its 

 skull, which is the heavier. The upper man- 

 dible of the red-head is less pronounced in its 

 superiority over the lower, than in the case 



