Sapsuckers WESTERN BIRDS 



suckers penetrate at least to the outermost layer of 

 sapwood, or non-growing part of the tree. This results 

 in the removal of the exterior rough bark, the delicate 

 inner bark, or bast, and the cambium. Since the elabo- 

 rated sap (upon which the growth of the tree depends) 

 is conveyed and stored in these layers, it is evident 

 that Sapsuckers attack the tree in a vital part. Each 

 ring of punctures severs at its particular level part of the 

 sap-carrying vessels, another ring made above destroys 

 others, and so the process continues until in extreme 

 cases circulation of elaborated sap stops and the tree 

 dies. When the injury to the vital tissue is not carried 

 so far, only a limb here and there may die, or the tree 

 may only have its vitality lowered for a few years. If 

 the attacks cease, it may completely recover. 



Recovery, however, does not mean that the tree has 

 escaped permanent injury. Patches of cambium of vary- 

 ing sizes may be killed, causing growth to cease at these 

 points and the dead and discolored areas are finally 

 covered by wood and bark. Until this process is com- 

 pleted, the tree is disfigured by pits with dead bark and 

 wood at the bottom, and even when completely healed, 

 the spot remains a source of weakness. In fact, all Sap- 

 sucker pecking is followed by more or less rotting and 

 consequent weakening of the wood, and renders trees 

 more liable to be broken by the wind or other causes. 



One effect of the working of these birds on a tree is to 

 cause a slight swelling of the bark which, if the bird 

 continues its operations, in time develops shelf-like 

 girdles. Then, too, buds are apt to start from the edges 

 of the holes drilled and in some cases produce so many 

 shoots as to disfigure the tree. 



Neither orchard, ornamental, nor forest trees are 

 spared by these birds and injuries done by them become 

 serious when they affect the commercial value of the 

 trees. The birds are fond of cone-bearing species and 



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