Notes on the Plumage of North American Sparrows 



SECOND PAPER 



By FRANK M. CHAPMAN 



(S.-e frontispiece.) 



Song Sparrow (Fig. 2). The fusing of tlie spots on the central breast-feathers 

 to make a larger spot or bK)tch and the pront)unced maxillary stripes are the chief 

 distinguishing marks of the eastern Song Sparrow, as well as of practically all 

 the races of Song Sparrow; add to these certain characteristics of voice and 

 manner, and a disposition which usually permits examination at close range, 

 and we have a bird which is generally identified without difficulty. 



The sexes are alike, and in view of the exceptional variations shown b\- this 

 species west of the Rockies, the color of our eastern bird is notably uniform. 

 It is a fact that the country east of the Rockies is in itself comparatively uniform, 

 but nevertheless there are in it areas inhabited by Song Sparrows the climate of 

 which differs more widely than that of regions in the West, each of which has a 

 different race of Song Sparrow. 



We have, it is true, a slightly grayer form (M. m. jiiddi) in North Dakota, 

 and specimens resembling this bird are not infrequently found in the Atlantic 

 coast states; but, on the whole, our bird shows but little individual variation 



The nestling has the wings and tail like those of the adult, but the body plu- 

 mage is softer, the streaks are less sharply defined, the breast blotch is wanting, 

 and the plumage is more or less suffused with yellowish buff. It is in this costume 

 that the young birds sing the low, indeterminate, rambling song so unlike the lay 

 of the adult. 



As Dr. Dwight has shown, in the paper before referred to, this plumage 

 may be worn for several months, the molt into the winter plumage occurring from 

 August to October. This molt includes all the body feathers, the tail, the tertials 

 and wing-coverts, usuall\- the primaries and rarely the secondaries. 



The adult, as is customary, passes from the breeding into winter plumage 

 by a complete molt, and is then indistinguishable from young birds in winter 

 plumage. Winter birds, aside from differences due to wear, have the breast and 

 sides more strongly washed with brcnvnish than do summer specimens. There 

 appears to be no molt in the spring, and the difference between sleek winter speci- 

 mens and much-bedraggled midsummer ones is due to wear. 



The Song Sparrow is the most plastic of North American birds, or, in other 

 words, it is so readily affected in size and color by the climatic conditions under 

 which it lives that, given some slight change in the climate of a region, we 

 expect to find it reflected in the Song Sparrow of that region. Broadly speaking, 

 the general colors of Song Sparrows are related to the rainfall, while their size 

 is related to latitude. Thus, the Song Sparrows of arid regions are pale, while the 

 Song Sparrows of humid regions are dark. Compare, for example, the figure 



(7O 



