142 A HISTORY OF BIRDS 



stores nuts. These insects are captured with as Httle injury as 

 possible, borne to some old oak post or tree, and there wedged 

 in between the crevices of the bark and left struggling vainly 

 to get free. As many as a hundred grasshoppers have been 

 found so wedged at one time. Later the birds return to devour 

 their victims. 



This record loses something of its importance at present, 

 since it does not appear to have been ascertained whether the 

 stores referred to are made by individuals or by a number of 

 birds banded together for a common purpose. 



In this connection mention may be made of the case of the 

 American Yellow-bellied Woodpecker {Sphyrapiaisvarius)w\\\ch. 

 has developed a great fondness for the sap of trees, to obtain 

 which it pierces a system of more or less symmetrically disposed 

 holes through the bark so as to tap the source of the sap. This 

 soon collects in the holes prepared for its reception, and, inci- 

 dentally, attracts large numbers of insects which are also devoured 

 by the Woodpecker. There is no record to show whether this 

 species also works in concert with its neighbours, after the fashion 

 of the Californian Woodpecker just referred to. 



The taste for sap is probably an acquired one, possibly gained 

 in the first instance when this was tapped in searching for insects. 

 The fact that insects became attracted to the sweet juice issuing 

 from these originally more or less accidental wounds in the 

 tree made by the bird, would soon, it may be imagined, be as- 

 sociated by the bird with the fact that only certain trees — apple 

 and maple, and one or two others — yielded this exudation, and 

 the consequent fly-decoy, as a result of vigorous hammering. At 

 any rate only profitable trees are so punctured, and hence this 

 bird in orchards is not much welcomed ! 



