GEOGRAPHICAL SURVEYS WEST OF 100TH MERIDIAN. 297 
that we come to consider as being necessary to the happiness if not the very existence 
of bird life, our little sparrow appears to be perfectly contented with its lot and un¬ 
mistakably expresses himself so in the unobtrusive but pleasant little songs he sends 
forth at odd tirnhs during the entire day. 
In what appears to be somewhat exceptional instances, this sparrow varies its habitat 
to a considerable extent. Thus I have occasionally found the summits of the high 
peaks to be occupied, together with a few other species, by the Brewer’s sparrow. 
The low brush or “ scrub” into which the luxuriant sub-alpine vegetation dwindles, as 
the higher altitudes on the mountains are reached, seem to offer conditions sufficiently 
similar to its more usual haunts to meet all requisites. In such spots the Brewer’s 
sparrows were often very numerous, while the presence of young birds sufficiently 
attested the fact that here was their summer abode. 
The nests of this sparrow are very much like the usual structures of the “ chippy,” 
but appear to be invariably placed in a low bush. Much variation appears in the shape as 
well as the markings of the eggs. The latter usually occur as blackish spots and 
blotches; these are generally few in number, and are mostly at the larger end, leav¬ 
ing the greenish-blue ground unoccupied for its greater part. Some specimens show 
no traces of black, but the spotting assumes a reddish-brown or neutral tint, often 
confluent in a ring at the larger end; Other sets have only a faint irregular freckling 
of the same. The smaller eggs exhibit a more or less decided pyriform shape, while 
those of larger size vary in the direction of a more elongated oval. The following 
measurements express these variations in size : (67x48) 2 , 68x47 ; (63x48) 2 , (62x4?)' 2 ; 
69x50, 68x52, 65x50, 69x53. 
Melospiza Baird. 
A study of the song sparrows of the United States and adjoining regions reveals an 
extraordinary amount of variation, coinciding more or less closely with definable geo¬ 
graphical areas. Others of our species are possessed of a similar wide range, but in 
no other are exhibited such marked variations of color and such mutations in size as 
in this. 
The song sparrow, although apparently nowhere a permanent resident, in the strict 
meaning of that term, that is, to the extent of the same individuals remaining in the 
same place throughout the year, is yet migratory to only a limited degree ; and it is prob¬ 
able that the change of locality with the migrations is, in the instance of none of the 
forms, very marked. It is doubtless to this localization and the resulting constantly- 
exerted influence of the same circumstances of environment, that we are to attribute the 
extraordinary tendency in this bird to develop into races and offshoots, according as its 
range brings it under differing conditions. As Dr. Coues happily phrases it, “Migration 
holds species true; localization lets them slip.” And nowhere is to be found a better 
illustration of this aphorism than is presented by the song sparrow. 
A recent examination of the extremely large collection of song sparrows iu the 
Smithsonian Institution, in connection with the extensive suite gathered by the Expe¬ 
dition, has developed some facts that appear to be of sufficient value and interest to 
warrant brief mention. Here as elsewhere the variation, through which the forms 
are indicated, are of two kinds, viz, a variation in size and a variation in coloration; 
nor is it easy to say in which direction the changes are most pronounced. 
The only song sparrow found in eastern United States, and which extends from the 
coast as far west as Nebraska and Indian Territory, isth M.melodia', and of all the forms, 
except possibly insignia, this appears to be the most constant in the maintenance of its 
peculiarities over its wide habitat. In fact, so far as color goes, the variation appears 
to be scarcely noticeable ; nor is the variation iu size very marked. Such as it is, it 
appears to bear out the general rule of an average increase of size to the northward. 
This law, it may be remarked here, appears to be equally applicable also to all the 
other races. The general sameness in the topographical character of the eastern re¬ 
gion and the resulting similarity of climate is doubtless the chief cause of the slight 
departure from type to be observed in melodia throughout its range. 
The Rocky Mountains as far to the north as Oregon and to the south to our southern 
border, and the entire region west to the Sierra Nevadas, is occupied by the var. fallax. 
This bird is distinguishable from melodia by a generally paler tone of coloration, by a 
decided increase in size, especially of wing and tail, and by a slightly longer and con¬ 
siderably more slender bill. The intergradation of this form with melodia is readily 
traceable and complete. From the very varied nature of the country occupied by fal¬ 
lax, it being broken up by lofty mountain ranges, and the ensuing differences of climate, 
considerable discrepancies might naturally be expected in specimens of this race from 
different localities. Such proves to be the case ; and, iu examining a large series, the 
attention is often arrested by some slight phase of color which is often so intaugible 
as to practically elude defluition, but which occasionally is sufficient to identify all 
the individuals from some one limited neighborhood. So frequently is this impression 
received, that it would almost appear as if each locality in the middle region furnished 
2 H 
