338 THE WOODPECKERS 



an answering response from some more or less distant part of the 

 wood, they have been supposed to be the accompaniments of court- 

 ing. This may be so, but they are also made on occasions of alarm or 

 of great excitement, as when the nest is being robbed. Thus Montagu 1 

 remarks that on one occasion, when a chisel and mallet were used to 

 expose the nest of a greater spotted- wood pecker, the female did not 

 attempt to escape till a hand was introduced into the nest, when she 

 quitted the tree by another opening, and " flew to a decayed branch 

 of a neighbouring tree and there began her jarring noise . . . which 

 was soon answered by the male from a distant part of the wood, who 

 soon joined his mate, and both continued these vibrations, trying 

 different branches till they found the most sonorous." The fact that 

 these strange noises may be heard at all times of the year l led some 

 ornithologists to believe that they were made to arouse insects, but 

 this interpretation is not supported by facts. As we have already 

 hinted, the greater spotted-woodpecker is not the only performer of 

 this kind, its smaller relative and the green-woodpecker being also 

 skilled in this matter. 



That the woodpeckers depart very widely in their structural 

 characters from all our other woodland birds is a matter of common 

 knowledge, but as to the details of this departure information is by no 

 means so general. In the first place, then, by the process known as 

 "adaptation," these birds have become transformed in certain par- 

 ticulars which are correlated with their peculiar mode of life. The 

 peculiar features, in short, which distinguish these birds seem to have 

 come into being in response to the needs of the organism, or, in other 

 words, to the demands of the environment. But though this interpre- 

 tation is in the main correct, we are yet far from understanding the 

 nature of the subtle action and interaction of the one upon the other. 



The external evidences of this adaptation are to be found in the 

 density of the beak-sheath, which serves as a pickaxe, the zygo- 

 dactyle feet and large claws, which form admirable climbing organs, 



1 Ornithological Dictionary, p. 541. ' That it is a fact is disputed. 



