boy, after hazarding his neck to reach the woodpecker's 

 hole, at the triumphant moment when he thinks the 

 nestlings his own, and, stripping his arm, plunges it down 

 into the cavity and grasps what he thinks to be the cal- 

 low young, starts with horror at the sight of a hideous 

 snake, and almost drops from his giddy pinnacle, retreat- 

 ing down the tree with terror and precipitation. 



Other carpenters are not equal to the woodpeckers, 

 either in skill or in strength ; they are, at the most, only 

 able to widen and extend holes which are already at 

 hand, or to work in decaying wood only. The black- 

 capped titmouse (Parus major) digs out a shallow hole 

 in the decayed side of an old stump in early May. Not 

 rarely, after working for a day or more, the pair encoun- 

 ter a layer of hard wood in the old weather worn stump, 

 and have to cease their efforts and seek a more suitable 

 spot, for the conical beak has not sujficient strength to 

 penetrate hard substances. The excavation is usually 

 about six inches deep and widened out to accommodate 

 the prospective family. Nearly one-half of the space is 

 then filled with the fluffy material of the nest. 



Close to the carpenters we must put the miners or 

 tunnel-builders, because they also make holes, though 

 not in wood, but in the ground, usually in the banks of 

 rivers, even in hard, rock-like material. Prominent 

 among them is the bank swallow or sand martin (Clivi- 

 cola riparia). Although its little beak and slender claws 

 would seem at first sight to be utterly inadequate for the 

 performance of miner's work, the sand martin is as good 

 a tunnel-driver as the mole or the rat, and can manage 

 to dig a burrow of considerable depth in soil that would 

 severely try the more powerful limbs of the quadruped 

 excavators. The soil which it loves most is light sand- 

 stone, because the labor which is expended in the tun- 

 nelling is very little more than that which would be re- 

 quired for softer soils, and the sides of its burrow are 



96 



