THE SAND-MARTIN S NEST. 



303 



than this, for having dug its hole, .it simply lays its eggs on the 

 earth at the extremity ; while the sheldrake, more regardful of 

 the comfort of her young, lays them on down picked from her 

 own breast. 



Other birds establish themselves in the trunks of trees, and, 



The Sand -Mar tin. 



like the earth-burrowers, either form their tunnels with their 

 own beaks, or appropriate to their use the excavations made by 

 other animals, or the hollows formed by natural decay. Among 

 these dendrobites, the woodpeckers, who by means of their 

 pickaxe- like beak scoop out deep caves in decaying trees, or 

 even in sound wood, hold a conspicuous rank. These nests are 

 frequently most ingenious, the burrow sloping for six or eight 

 inches, and then being driven perpendicularly down the tree. 



