The Bird Department 



By Arthur A. Allen. 



[Without birds to wage war upon insects, the insect hordes would increase so enormously that they would destroy 

 all the vegetation in the world and then what would become of the human race? This department will be devoted to 

 public education on birds and each month will be given advice and instruction for their care and for encouraging bird 

 life. Editor's Note.] 



BIRDS AND THE FORESTS 



WHEN the world has once more regained its 

 equiHbrium and the great powers have again 

 settled down to constructive policies, one of 

 the questions that will be brought forward is that of 

 international legislation for the protection of migratory 

 birds. It will be a natural outgrowth of the struggle 

 which the United States has witnessed during the past 

 few years between the commercialist and the conserva- 

 tionalist, a struggle that has resulted in national legisla- 

 tion giving our birds a more wide-spread encouragement 

 and protection than has ever before been possible. 



Had the battle in this country been waged along the 

 lines of sentiment alone, with which these birds are so 

 often and so rightly associated, our practical legislators 

 could never have felt justified in enacting these far- 

 reaching measures. Fortunately, the science of orni- 

 thology had already advanced to a stage where it could 

 state definitely the important role played by the birds in 

 protecting crops, orchards, and forests. The Biological 

 Survey in Washington and economists in all parts of 

 the country had been studying the food of birds for 

 some thirty years, with the result that the issue was one 

 of real economics rather than one of sentiment. 



There are few people today that are uninformed as to 

 the value of birds. The annual loss of over 700 millions 

 of dollars to agriculture in this country due to the 

 ravages of insects and the part taken by the birds in 

 destroying these pests are familiar facts. The birds are 

 nature's guards, appointed to keep the wonderfully pro- 

 lific insects from overrunning the earth, and, when one 

 stops to consider that a single pair of potato beetles, if 

 uncontrolled, would at the end of a single season result 

 in sixty million offspring; or that a single female plant 

 louse could give rise in the twelve generations which 

 occur each year to over ten sextillion young, one is forced 

 to acknowledge the invaluable asset we have in the birds. 



In the garden, however, and in the orchard, it is 

 usually possible by artificial means to battle successfully 

 with insects. Poisonous sprays and cleverly contrived 

 traps with sufficient output of time, labor and expense, 

 will, in most cases, keep the farm in profitable condi- 

 tion. But the whole world is not a garden. It is obvi- 

 ously impossible to exterminate all insects. Human 

 ingenuity will never devise profitable means for spraying 

 the forests or trapping the forest insects. Over 500 

 species of insects prey upon the oak trees alone and 

 nearly 300 upon the conifers, any one of which, if left 

 uncontrolled, would destroy the trees. 



When experiments were being carried on in Massa- 

 chusetts with the raising of the American silkworms 

 (Telea polyphemiis), the larvae of which feed upon a 

 number of shade trees, a striking demonstration of the 

 danger from these tree-inhabiting caterpillars was 

 given, for it was discovered that each caterpillar required 

 120 oak leaves to reach maturity. If all the eggs laid 

 by a single moth should all hatch and reach maturity, 

 few oak trees would be large enough to support a single 

 family. Fortunately, however, it was discovered, at the 

 same time, that in a state of nature 95 per cent of the 

 larvae are destroyed by birds. 



Again, in Dakota, when the first attempts were made to 

 grow trees upon the prairie lands, the experiments re- 

 sulted nearly in failure because of the ravages of this 

 silk worm and closely allied caterpillars, the reason for 

 their destructive numbers being the absence of arboreal 

 birds. This is a problem which always presents itself 

 in the reclamation of waste lands by the planting of trees 

 where tree-frequenting birds are not yet established. It 

 is fortunate that many birds are quick to avail them- 

 selves of new territory and that a number of species 

 have extended their ranges during recent years, follow- 

 ing the reclamation of arid country. 



But even where birds are established it happens occa- 

 sionally that some insect plague escapes the control of 

 its natural enemies and we have the great destruction 

 wrought by the gipsy and brown-tail moths in ^lassachu- 

 setts, and the defoliation of the shade trees in many of 

 our eastern cities by canker worms, tussock moths, elm- 

 leaf beetles, and tent caterpillars. But during these 

 devastations two facts have been repeatedly noticed. 

 First, the outbreaks have -always begun among the shade 

 trees of our cities where birds are conspicuously scarce, 

 and, second, spots to which birds have been attracted 

 have sufl?ered the least. 



In this connection the experiments of Baron von Ber- 

 kpsch on his estate in Germany, in attracting birds and 

 maintaining a number far in excess of the surrounding 

 country, have become almost classic. By putting tip 

 thousands of nesting boxes throughout the forest to 

 replace the dead trees which are required by hole-nesting 

 birds, by introducing food-bearing plants, shrubs and 

 trees, by feeding the birds during winter and times of 

 stress, and by destroying their natural enemies, he so 

 increased their numbers that, when an insect plagfue 

 spread over the country, his estate was the one green 

 spot upon the entire landscape. Such a convincing 



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