394 



ZOOLOGY 



ferent from the original robin redbreast of 

 England. The bluebird is typically American, 

 and is unknown in Europe. 



It is scarcely possible to exaggerate the importance of 

 birds for mankind. Aside from the value of their bodies 

 as food and their feathers as ornament, they serve as 

 the constant guardians of our crops. While an occa- 

 sional hawk may raid the barnyard, and the cherries 

 may suffer from the robins, all the damage done by 

 birds to human interests is insignificant in comparison 

 with the benefits conferred. The normal increase of 

 injurious insects is sufficient to maintain each kind in 



Photograph by E. R. Warren 



FIG. 167. Western robin (Planesticus migratorius propinquus), Monument 

 Valley Park, Colorado Springs, Colorado. This bird belongs to the thrush 

 family, Turdidse, and is very different from the true robin of England. It goes 

 southward in the winter, returning early in the spring, though in Colorado a few 

 birds remain throughout the year. Note the long bill, well adapted to the capture 

 of cutworms in the soil. In Colorado it has seemed to us that the cutworms were 

 worst when the ground was long covered by snow in spring, and we have thought 

 that this might be largely due to the protection they thus gained from the robins. 



