1394 U.S. NATIONAL MUSEUM BULLETIN 23 7 part 3 



uniformly with respect to all features of internal structure. Some 

 characters, however, are evidently closely correlated geographically 

 with other characters of internal structure." His most striking osteo- 

 logical finding was that: "In every case the samples with large bones 

 in the wings and pectoral girdle belong to races which have long migra- 

 tion routes and the samples with those bones weakly developed belong 

 to relatively sedentary races." 



As a part of this study Linsdale also analyzed many aspects of the 

 life history of the various forms, based on the published literature, 

 available museum material, and his own experiences with the bird 

 afield. From this analysis he concludes: "A consideration of the 

 available material bearing on the natural history of the fox sparrow 

 shows several well marked tendencies to vary geographically in habits 

 and in responses to the environment. These tendencies to vary follow 

 a definite order and parallels may be pointed out between them and 

 tendencies to vary in features of structure." Nevertheless the only 

 variations in "life history" features he enumerates are the following: 



Under the head of summer habitat it seems reasonable to expect some expression 

 of differential choice which may be correlated with change in geography. It is 

 evident that not only is there a differential habitat choice through the range of 

 the species but that, in general, the areas of uniform habitat correspond to the 

 ranges of various subspecies. For example, in the schistacea group of subspecies 

 the three smallest forms, in the Great Basin mountain ranges, are rather closely 

 limited in summer to the narrow fringes of willow, aspen, and birch which grow 

 along the streams on dry mountain sides. Farther west, in the California moun- 

 tains, the birds are found scattered through the dense growths of chaparral on the 

 high slopes. In the north where the climate is more moist the birds are found in 

 various types of brushy vegetation in different localities, but everywhere the 

 habitat is different from those of the southern races. 



* * * 



The songs of fox sparrows, considered from a geographic point of view, show 

 tendencies to vary that may be correlated with differential choice of habitat and 

 with structural differentiation. The species, as a whole, is especially noted for 

 its highly developed vocal powers. There is, however, an easily distinguished 

 gradation of volume and quality among the races of at least the schistacea group. 

 The song of the smaller races in the Great Basin resemble that of some song spar- 

 rows more than that of some of the closely related fox sparrows in the territory 

 to the west. 



The rather bulky nests of this bird are usually so well hidden as to be found with 

 difficulty. They are placed in numerous types of situations although usually near 

 the ground. There appears, from incomplete information, to be a tendency for 

 birds in the northern parts of the range to place their nests higher than do those 

 to the southward. This might be partly due to necessity since in the south most 

 of the available nest sites are within a few inches of the ground. A great variety 

 of material is used in the construction of the nests. 



There is a considerable amount of individual variation in respect to color in 

 the eggs of this species. The eggs are, in every way, strikingly similar to those 

 of the song sparrow. Records are sufficiently numerous to show that in the 

 northern part of the species' range four is the usual number of eggs and five are 



