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THE NATIONAL GEOGRAPHIC MAGAZINE 



branches and examine each crack and 

 crevice in the bark for eggs or larvae, 

 others devote their energies to the twigs 

 and foliage, scanning each leaf and stem 

 with eager eyes. Still others descend to 

 the ground and examine the rubbish and 

 grass for hidden prey, while nearly all 

 are adept at catching insects on the wing. 



Each species, however, has a method 

 of its own, more or less unlike that of its 

 fellows, and each excels in some specialty. 

 Not only does the group as a whole spe- 

 cialize on insects, but each individual 

 member of the group still further special- 

 izes, so as to leave no loophole for the 

 escape of the enemy. 



The quantity of animal food required 

 to drive the avian engine at full speed is 

 so very great that it is no exaggeration 

 to say that practically all the waking 

 hours of our warblers, from daylight to 

 dark, are devoted to food-getting. What 

 this never-ceasing industry means when 

 translated into tons-weight of insects, it is 

 impossible even to guess, but the practical 

 result of the work of our warblers and 

 other insectivorous birds is that we still 

 have our forests, and shall continue to 

 have them so long as we encourage and 

 protect the birds. 



In the case of orchards and shade trees, 

 there are other means at our disposal of 

 controlling the insect enemy, notably the 

 use of sprays. Sprays are very impor- 

 tant, since birds are too few in number 

 immediately to control insect outbreaks, 

 especially nowadays, when the number of 

 destructive native insects has been so 

 greatly increased by importations from 

 all quarters of the globe. But for the 

 preservation of our forests we must rely 

 largely upon our birds, since the use of 

 sprays or of other agencies over our vast 

 woodland tracts would be too expensive, 

 even were it not quite impracticable for 

 many other reasons. 



MEANS OF INCREASING THE NUMBER OE 

 WARBLERS 



Insects are very numerous, and there is 

 reason to believe that much benefit would 



result if we could multiply the present 

 number of their enemies — the birds. The 

 erection of bird boxes and shelters is an 

 easy way to increase the number of cer- 

 tain species of birds, like swallows and 

 chickadees. Unfortunately, with few ex- 

 ceptions, our warblers do not build their 

 nests in cavities, and hence can not be 

 induced to occupy bird boxes. 



Many of them, however, nest in bushes, 

 vines, and shrubbery, and by planting 

 clumps of these near houses something 

 can be done toward increasing the num- 

 bers of certain species, as the yellow 

 warbler and the redstart. Because our 

 warblers are chiefly insectivorous, their 

 food habits bar them from the usual bird 

 lunch-counter in times of hard storms. 



During migration, warblers are pecu- 

 liarly exposed to the danger of prowling 

 cats. Many species feed close to or even 

 on the ground, and then they are so much 

 concerned with their own business that 

 any tabby, however old and lazy, is equal 

 to catching one or more individuals daily. 

 The bird lover can do good service by 

 summarily disposing of vagrant cats, 

 which, during migration, work havoc in 

 the ranks of our small birds. 



They can also restrain the pernicious 

 activities of their own pets, for these, 

 however well fed, are still subject to the 

 predatory instincts of their wild ancestry, 

 which impel them to stalk a live bird with 

 all the zeal and cunning of their fore- 

 bears. 



PLUMAGES OE WARBLERS 



Little difficulty is experienced, even by 

 the tyro, in distinguishing w T arblers from 

 other birds, but to recognize the several 

 species is not so easy, particularly as the 

 adult males and females of many species 

 are markedly dissimilar, while the young, 

 both in the first and second plumages, 

 often differ from the adults. So far as 

 possible the various plumages are shown 

 in the illustrations of the artist, which 

 are so admirable as to do away with the 

 need of descriptive text. All are ap- 

 proximately one-half life size. 



