100 USEFUL BIRDS. 



are subject to a more or less regular periodical pruning. 

 Large quantities of twigs and small branches fell from the 

 oaks and other trees in 1896, and it appeared as if the 

 oak pruners might do considerable injury to these trees ; 

 but birds and other natural enemies attacked the insects, 

 and the trees were not injured, very likely in most cases 

 they were even benefited by this removal of the twigs from 

 the upper branches. Jays, Crows, and Hawks break off 

 strong twigs and small branches to use in their nest build- 

 ing. Squirrels gnaw off many twigs while gathering nuts 

 and acorns, or while building their nests. When branches 

 are injured by insects or overshading to such an extent that 

 they die, they are removed later (when weakened by decay) 

 by the action of the wind, or are broken off in winter by 

 ice and snow. Thus the pruning of the trees is effected. 



THE GUARDIANS OF THE TREES. 



Birds guard the Trees the Year round. We know that 

 trees are subject to many injuries by reason of the undue 

 multiplication of animals that feed upon them. The foliage 

 is devoured by insects and other animals ; the fruit and 

 seeds by insects, birds, and squirrels ; the twigs are killed 

 by borers or girdlers ; the bark is eaten by mice, hares, squir- 

 rels, or porcupines ; the trunks are attacked by wood ''borers ; 

 the roots have insect enemies ; even the very itfe blood, the 

 sap, is sucked out by aphids. When we consider well the 

 fecundity, voracity, and the consequent great possibilities 

 for mischief possessed by their enemies, we wonder that 

 trees survive at all. Still, trees spring up and grow apace. 

 In a wooded country a few years' neglect of field and pasture 

 suffices to clothe them with a growth of bushes and saplings, 

 and in time a wood lot succeeds the cleared land. That 

 trees are able thus to spring up and grow to maturity with- 

 out man's care is sufficient evidence that they are protected 

 by their natural friends from the too injurious inroads of 

 their natural enemies. Among these friends birds hold a 

 high place. 



It is generally believed that there are few birds in deep 

 woods. Travellers often have remarked the scarcity of birds 



