224 



AMERICAN FORESTRY 



cottony cradle of the yellow 

 warbler, arc, perhaps, the 

 most unusual of the war- 

 blers' nests, the others being 

 fashioned of grasses, root- 

 lets, leaves, and other 

 common materials into the 

 ordinary cup-like fonn. The 

 eggs of the warblers are 

 remarkably uniform, being 

 creamy-white, more or less 

 spotted with brown, and it 

 requires ten or eleven days 

 for them to hatch. The 

 young remain in the nest 

 from eight to twelve days 

 but are cared for hy their 

 parents for some time 

 thereafter, since only one 

 brood usually is raised in 

 a season. 



To the warblers is given 

 the care of the foliage of 

 the trees and therefore the 

 good health of the forest. 

 They are the tree doctors 

 just as the woodpeckers are 

 the tree surgeons. As long as the foliage is kept in gocd 

 condition the trees will be healthy and produce good wood. 

 Conifers will scarcely stand a single defoliation and de- 

 ciduous trees are seriously devitalized even by a single 

 stripping of the leaves. Never a year passes when suffi- 

 cient caterpillars are not hatched to defoliate every wood- 

 land in this country, so prolific are the moths which lay 



A CO.VFIDING CHESTNUT-SIDED W.\RBLER FEEDI.MG ITS Y0U\G 



Many of the warblers are apparently without fear of man and do not hesitate 

 to feed their young even when held in the hand. 



the eggs. It is possible and 

 practical, nowadays, to 

 spray the shade trees of city 

 streets and thus protect 

 them from these pests, al- 

 though it is always an ex- 

 pcnsi\-e process, but it will 

 never be practical to spray 

 entire woodlands. We must 

 continue to rely upon the 

 protection which birds give. 

 Chief among these arboreal 

 guardians are the warblers, 

 and the thoroughness with 

 which they do their work can 

 be proved by any one who 

 will observe a tree infested 

 with the canker worms, 

 aphids, gypsy moths, or al- 

 most any other pest of the 

 foliage. Once the migratory 

 troops of warblers discover 

 it, they will remain about it 

 for days, new birds fre- 

 quenting it all through 

 the migrating season, until 

 the cateriDillars become so 

 scarce that they are difficult to find. The number con- 

 sumed by a single bird seems almost incredible, but much 

 careful and accurate infonnation has been accumulated 

 by E. H. Forbush, the State Ornithologist of Massachu- 

 setts, giving actual numbers consumed, which attest the 

 tremendous economic importance of this family. 



Mr. R. PI. Coleman counted the number of insects 



"WOOL G.\THERIXG" 



The yellow warbler and the redstart can be encouraged to nest in the garden 

 by supplying them with nesting material. Here a yellow warbler is taking 

 some cotton that has been put out for it. 



A CA.N'ADIAN LU.NCHEON 



A Canadian warbler bringing a crantfly to its young. The Canadian warbler 

 is one of the common warblers of the north woods. 



