1913] Grinnell-Swarth: Birds and Mammals of San Jacinto 257 



bird of this region is not Empidonax griseus Brewster, as it has 

 heretofore been considered. Large, gray-colored birds appar- 

 ently referable to this latter species occur regularly in southern 

 California during the migrations, and in winter, but are never 

 seen during the breeding season nor in the high mountains, while, 

 on the other hand, individuals of the wrighti type are of 

 extremely rare occurrence away from their nesting ground in 

 the Boreal zone. The fact that the wandering examples of 

 grist us are usually in quite fresh plumage, while of the summer 

 specimens of wrighti in our collections a large proportion are 

 juvenals, and the adults mostly in very worn condition, though 

 the color differences are thereby accentuated, gave the impres- 

 sion that these differences were mostly seasonal, or from wear. 

 All the southern California breeding birds, however, are of the 

 smaller size, with shorter, broader bill, and brown-colored lower 

 mandible, characteristic of wrighti, while the migrants from 

 the lowlands of the region which we now regard as examples of 

 grist us, are of larger size, with longer and more slender bill, 

 and with light-colored lower mandible. 



It appears, therefore, that both species occur in southern 

 California, griseus as a regular but rather uncommon migrant 

 and winter visitant in the valleys, more commonly on the desert, 

 and wrighti as an abundant summer visitant in the comparatively 

 limited area of high Transition and Boreal of the mountains. 

 The fact that the latter species is of exceedingly rare occurrence, 

 almost unknown, in the lowlands of the region, points to 

 similar habits of migration to those of Passerella i. stepht nsi, 

 and Orcospiza chlorura, occupying precisely the same summer 

 habitat. All three species depart from the region in fall and 

 enter again in the spring, without visiting the adjacent plains 

 and valleys. 



The similarity of wrighti and griseus, both in appearance and 

 habits, is such as to have caused them for years to be confused. 

 but there is little doubt but that there are two such distinct 

 forms, though the occurrence of numerous individuals with diffi- 

 culty allotted to one or the other species seems to indicate the 

 possibility of intergradation between them. Such intergradation. 

 indeed, was pointed out by Brewster (1889, p. 88), in his descrip- 



