840 



The Sparrow-like Birds 



has proven so sensitive to influences of physical environment, and as a result 

 of this plasticity of organization it has become divided into a large number of 

 geographical forms, some of extensive, others of very circumscribed, range, the 

 area of distribution in every case coinciding strictly with uniformity or con- 

 tinuity of physical conditions. Thus the form having the widest distribution is 

 that inhabiting the Atlantic watershed, or the entire region from the wooded 

 valleys of the Great Plains eastward, while those of most limited range belong 

 to the Pacific slope, where the topographic and resultant climatic features are 

 so varied and complicated. In California, for example, practically each dis- 

 tinct drainage area has its own peculiar form, one being strictly limited to the 

 salt marshes fringing San Francisco Bay. From the last-mentioned point, in- 

 habited by decidedly the smallest of all the subspecific forms, northward along 



the coast there is a gradual 

 change, the size steadily in- 

 creasing, the plumage be- 

 coming first more rusty, then 

 more sooty, and finally more 

 grayish, until the extreme 

 limit of variation is reached 

 in the gigantic Aleutian Song 

 Sparrow of the Shumagin 

 ; %^^~ an< ^ Aleutian islands." 



The Song Sparrow, es- 

 pecially the eastern form 

 (M. melodia), is one of the 

 best known and most wel- 

 come of our bird visitors, 

 often seeking^the proximity 

 of houses, where they build their nests and rear their young within a few feet 

 of constantly passing people. The nest is a neat affair placed in a low bush, 

 hedgerow, or on the ground, and the eggs, usually four or five, are dull white 

 much spotted with darker. The song is delightfully sweet and may be heard 

 from earliest spring to latest fall. 



Swamp Sparrow. The other species are the Swamp Sparrow (M. georgiana) 

 of the eastern United States and Lincoln's Sparrow (M. lincolni) of the western 

 United States. 



The Juncos (Junco) form another typically American group of some twenty 

 forms. They are small birds, about six inches in length, the adults plain gray 

 above, often darker on the head, and plain grayish or whitish below. The 

 lateral tail-feathers are largely white and form a conspicuous feature when the 

 bird is in flight. They are strictly granivorous, frequenting hedgerows, weedy 

 fields, and gardens. The best-known and most widely distributed form is the 

 Snow-bird, or Slate-colored Junco (J. hyemalis), which is found over entire 

 North America, though rarer in the western portions, breeding from the moun- 

 tains of Pennsylvania, New England, and Michigan northward to Labrador, 



FIG. 231. Song Sparrow, Melospiza melodia. 



