192 OUR BIRD ALLIES. 
observer that only by craft can he contrive to watch 
them while engaged in their labours. Even careful 
concealment and perfect quiet upon his part will not 
always suffice to re-assure the bird, for I have more 
than once attempted to watch a woodpecker whose 
tapping I had distinctly heard, and yet failed, although 
waiting for fully half an hour, to catch sight of it 
after all. 
The burrow, if we may so call it, in which the wood- 
pecker brings up its family is only large enough to 
admit the bodies of its constructors, who collect the 
chips cut away during the process of excavation, and 
form a rude nest, or rather heap, with them at the 
extremity. Upon this primitive bed five or six glossy 
white eggs are laid. It is a rather curious fact that 
the young birds are able to run about on the upright 
trunk some little time before they are full-fledged, 
retiring to the nest if threatened by sudden danger, 
or if they should be in want of food. The burrow, 
by the way, is, perhaps, more offensively odorous than 
the habitation of any other living animal, without any 
exception whatever. 
THE Cuckoo, again, deserves honourable mention on 
account of its insect-hunting proclivities, its food 
consisting, in great measure, of various destructive 
caterpillars. These it devours in considerable num- 
bers, and, if the stomach of the bird be opened, it is 
almost sure to be found lined with the hairs of such 
caterpillars as the Woolly Bear, or others of an 
equally hirsute and voracious character. Larve 
