180 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
constantly from aestiva of eastern North America in having the chestnut 
streaks on the under parts narrower and fainter —in this respect showing an 
approach to sonorana, from which, however, it may be readily distinguished by 
the decidedly darker, greener coloring of its upper parts. The female is similar 
to aestiva (although less often streaked beneath) and hence quite different 
from that of sonorana, which is grayish above and clay-colored beneath, with 
but faint traces of yellowish on the body plumage. On the whole the Yellow 
Warbler of California seems to me too nearly like true aestiva to be recognized 
as a distinct subspecies. In any case it should not be called morcomz. At 
least Mr. Ridgway and I agree in considering the type of that supposed form 
merely an exceptionally faintly streaked specimen of aestiva, of which, more- 
over, the National Museum possesses a number of perfectly typical examples 
from the same general region (i. e. Utah and Montana) one of them being 
actually from the same locality (Fort Bridger). 
Mr. Frazar found the Yellow Warbler rather rare in January and February 
at La Paz, where it frequented the shrubbery in the town gardens. It was not 
noted after March 1 (save on April 21, when one was seen at Triunfo) until 
August 28, when it was again met with at San José del Cabo. Here it became 
common by the latter part of September, but it kept so closely concealed in 
dense thickets as to be much oftener heard than seen. A single specimen was 
also taken at Santiago on November 16. To the northward of La Paz it does 
not seem to have been observed by any one except Mr. Anthony, who “says 
it is common on the northwest coast up to 2,500 feet altitude ” (Bryant), 
and “ common during migration in the valleys and as a summer resident in the 
higher altitudes,” on San Pedro Martir.? 
The Yellow Warbler breeds plentifully on the Pacific coast from southern 
California to Washington, being replaced in British Columbia and to the north- 
ward by the closely allied subspecies, rubiginosa. It is not known to occur 
north of the southern boundary of the United States during the winter months, 
when it migrates to Central America and the more northern portions of South 
America. 
Dendroica aestiva sonorana Brewst. 
Sonora YELLOW WARBLER 
(t) Dendroeca aestiva Hanae Proc. U. S. Nat. Mus., V. 1883, 4536, part (Cape 
Region). 
(2) Dendroica aestiva Bryant, Proc. Calif. Acad. Sci., 2d ser., II. 1889, 809, part 
(Cape Region). 
Among the Yellow Warblers collected by Mr. Frazar there are, as I have just 
stated in another connection, four young females killed at San José del Cabo — 
on October 5, 12, 20, and 27 respectively — which are perfectly typical speci- 
1 Anthony, Zoe, IV. 1893, 244. 
