NATURE STUDY IN SCHOOLS. 



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base, as in the warblers. Why, it may be asked, are the vireos so fettered 

 as to cause them to be less active than many other species of small birds : 



If we think a moment we shall see that this very inactivity may prove 

 advantageous to the birds, as caution in movement may enable a bird to steal 

 upon an insect, for example, and thus capture it more readily than if it 

 moved with greater rapidity. That is, vireos have found it advantageous to 

 move slowly in search of their prey, and thus their feet have become mod- 

 ified to suit this method of movement among the branches. There can be 

 but little doubt but what a vireo, with its peculiarly constructed feet, is ca- 

 pable of grasping a twig more firmly than is a warbler with its free toes. 

 This fact, together with the large bill, with its powerful jaw muscles, would 

 enable the vireos to capture and kill large caterpillars more readily than could 

 a bird which is not provided with similar appendages. 



Fig. 70. 



Head of Pine Warbler. 



Comparative deliberation of movement, then, is one characteristic of the 

 vireos, but I have here to state that even among the vireos there is a differ- 

 erence in this respect, and that we do have one group of vireos which, as 

 vireos, moves more actively than another group* Strange to say also, the 

 group of vireos which is a little the more active, sings a little more ener- 

 getically than the other group. Then again, correlated with these two char- 

 acters we find that all of the energetic vireos have wing bands, and that 

 they are absent in members of the other group. 



While it is possible that this division into groups may be extended to 

 all other species of this particular genus ( Vireo ) I will now simply apply 

 it to the species which occur in New England. We thus have : 



Vireos. Plainly colored birds, less than six inches and a half long, 

 with large bills, hooked at tip, large heads, and partly fettered toes. The 

 outer primary, or first quill of the wing is always shortened. As seen in the 



