TYPES OF NESTS OF BIRDS. 235 



or reti-eat known as home, we may well wonder at the power of the im- 

 pulse or Instinct that leads them to build a strong dwelling for use but 

 several weeks at most, and confine their activities to a limited range. 



The knowledge of nest-building manifested by the birds is doubtless 

 inherited. This theory is strengthened when we learn that birds of the 

 same species construct nests of the same general type, following a com- 

 mon pattern of architecture and using materials of similar texture. A 

 robin's nest in Montana differs in no essential feature of structure or ma- 

 terial from one in Illinois or New York, and generation after generation 

 of robins construct nests of the same typical style. If a robin be taken 

 fi'om the nest and reared apart frorn other robins, its attempts at nest- 

 building will follow the plan approved by years of robin experience. 

 Therefore when the bird-student becomes familiar with the type of nest 

 constructed by any species of his avian friend, he will be able to identify 

 the nest of that species thereafter with little difficulty. 



After selecting a convenient crotch of some tree not far removed from 

 civilization, the robin makes a substantial foundation of dried grass, 

 strings, rags, or other similar material. Upon and within this Mrs. Robin 

 erects a strong mud wall, smoothing it interiorly by rubbing and molding 

 it with her breast. Then she places a bedding of coarse dried grass 

 in the bottom of her cot, and she has a habitation as comfortable as a 

 prairie settler's dug-out. 



Among the nest-builders of the Flathead region, the olive-backed 

 thrush is quite abundant. It selects a site near the top of a small fir 

 tree, from six to ten feet from the ground, or in an upright crotch of a 

 slender sapling, generally in the edge of a swamp or retired woods. The 

 base of the nest (Fig. 17) is a loose mass of dried grass and weed-stems, 

 upon which the builder forms a snug-walled structure of dark-green 

 lichen and fine dried grass, the latter also serving as lining for the nest. 

 It is said that in more northern localities a larger proportion of moss and 

 lichen is used by this thrush, but the type of architecture is character- 

 istic wherever the thrush is found nesting. 



Belonging to the same genus as tne olive-backed is the willow thrush. 

 It is the rule that birds of the same genus have similar habits of nidifica- 

 tion, but the willow thrush differs very materially from its congener in its 

 plan of architecture. It uses very coarse weed-stems and strips of bark, 

 pine needles, and dried leaves, all dark material, making a thick-walled 

 cup generally deeper than the work of the olive-backed, lining it with 

 dark root-fibers. This nest is genei-ally placed on or near the ground, 

 frequently on a heap of decaying leaves or similar rubbish. In 1902. how- 

 ever, a nest of this thrush was found six feet from the ground, in an 

 upright crotch of an oblique sapling, a very unusual situation for the nest 

 of the willow thrush. 



The catbird is one of the common birds of this portion of the Flat- 

 head region. Its nest is made in a low bush, usually among upright 

 stems. It is a bulky structure, also made of dark material. Like the 

 willow thrush, the catbird uses strips of coarse bark, weaving them into 

 a strong basket, which it lines with coarse rootlets. Pieces of dried 

 leaves, and fragments of twigs are also used in the framework of the 



