THE WOODPECKERS :: 



And now let us return to the matter of the density of the beak. 

 We have already hinted that on occasion a weapon such as it is of 

 the greatest service in dislodging insect lame buried in the trunks 

 of more or less decaying trees, but insect prey of such a kind does not 

 fonn the staple diet of these birds, hence we cannot trace the peculiar 

 density of the beak-sheath to its occasional use for such a purpose. It 

 would seem, then, that we must ascribe such a structural peculiarity to 

 the fact that these birds choose as their breeding-places the interior 

 of trees which, while hollow at the core, have more or less sound 

 wood externally, which must be hewn away before the desired cavity 

 can be reached 



Ike green-woodpecker, in searching for a nesting site, will com- 

 mence many borings before finding a suitable site : and in the work of 

 excavation it displays a certain amount of individuality. Some will 

 elect to establish a nursery at not more than three feet from the ground, 

 but as a rule they ascend some twenty feet, and will sometimes retuni 

 to the same hole in successive years, even in cases where the original 

 entrance has been enlarged by human agency. 



Some birds take the precaution to carry away the tell-tale chips 

 which have fallen to the ground during the work of excavation, but 

 this display of caution appears to be the exception rather than the 

 rule. A tree is always selected which is decayed at the core, though 

 more or less sound wood may surround that cavity. It is probably 

 when the sound wood is thicker than estimated that holes which have 

 been cut for some distance are eventually abandoned But when 

 once the work is in full swing, the first or horizontal portion of the 

 tunnel is soon completed, then it takes a sudden downward turn, de- 

 scending about twelve inches, the eggs being deposited on the rotten 

 wood at the bottom without any further preparation for their recep- 

 tion. Laborious as this work of tunnelling must be, it is yet performed 

 with remarkable speed. Mr. J. E. Halting ' on one occasion kept a 

 pair of these birds under observation during the whole of this im- 



1 Halting, Uird of Middlnnc. 



