2 BULLETIN 171, U. S. DEPARTMENT OF AGRICULTURE. 



Hyloclchla) , there will be discussed in the present paper the food 

 habits of members of the five species of American robins and blue- 

 birds — the common robin (Planesticus migratorius) , the varied 

 thrush, or Oregon robin (Ixoreus nmvius), the eastern bluebird 

 (Sialia sialis), the western bluebird (Sialia mexicana), and the 

 mountain bluebird (Sialia currucoides) . While the ranges of these 

 birds in their subspecies extend entirely across the continent, the best 

 known are the common robin and the eastern bluebird. Time and 

 the further advance of cultivation into wilder areas may bring the 

 other species into greater prominence. 



The American robin (Planesticus migratorius and subspecies) is 

 one of the most familiar birds of the whole United States; and in the 

 extreme northwest there is found also the varied thrush, or, as it is 

 locally known, the Oregon robin (Ixoreus nmvius and subspecies). 



The eastern bluebird (Sialia sialis and subspecies) occupies the 

 whole of eastern United States west to the base of the Rocky Moun- 

 tains, and occurs also in southern Arizona; it is replaced beyond 

 the mountains by two western species (Sialia mexicana subspecies 

 and Sialia currucoides), which have much the same appearance and 

 habits. 



As robins and bluebirds are usually abundant wherever found the 

 matter of their food supply deserves careful consideration, for 

 wherever nature's lavish provision fails these birds must seek their 

 subsistence either from cultivated crops or from the wild varieties 

 especially left or provided for them by their human friends. A 

 determination of the nature of their food therefore becomes of con- 

 siderable economic importance. In the following pages is discussed in 

 detail the economic status of the five species of these groups of birds. 



ROBIN. 



(Planesticus migratorius and subspecies.) 



The common robin is probably the most familiarly known bird in 

 the United States and has embellished the literature of its rural life 

 to a greater extent than all other birds together. Having been made 

 the object of a transferred affection it has received the love and pro- 

 tection which the ancestors of the American people formerly lavished 

 upon the robin redbreast of Europe. The subspecies Planesticus 

 ■migratorius migratorius is found throughout the United States east 

 of the Great Plains and north of the Gulf States ; and elsewhere are 

 two closely related subspecies, one of which, Planesticus migratorius 

 propinquus, is well known in the valley regions of the Pacific coast 

 in winter and throughout the higher mountains in this section in 

 summer ; and the other, Planesticus migratorius achrusterus, is found 

 in the higher regions of southeastern United States. The range of 

 the species extends northward into Canada and even into Alaska. 



