186 BULLETIN 203, UNITED STATES NATIONAL MUSEUM 



are compactly woven cups generally placed from 3 to 10 feet above 

 ground, sometimes 15 feet, in rosebushes, willows, choke cherries, 

 hawk-berries, oaks, young cottonwood or boxelder trees, usually 

 within a short distance of the water's edge. The nest is usually com- 

 posed of gray plant fibers, bark shreds or grasses and is usually lined 

 with some downy substance such as cottonwood or willow cotton or 

 hair." 



DENDROICA PETECHIA BREWSTERI Grinnell 



CALIFORNIA YELLOW WARBLER 



HABITS 



The 1931 A.O.U. Check-List gives the breeding range of this sub- 

 species as the "Pacific coast strip from western Washington south 

 through Oregon and California, west of the Great Basin and south- 

 eastern deserts to about lat, 30° in Lower California." It intergrades 

 with ruhiginosa on the north and with nwrcomi to the eastward, but 

 exact boundaries are difficult to define. It seems to range well up into 

 the mountains, for James B. Dixon tells me that he has found it nesting 

 in Mono County, Calif., at altitudes of 6,500 to 9,200 feet. 



Dr. Joseph Grinnell (1903) in an interesting study of western yellow 

 warblers, bestowed the above name on the California bird, for which 

 he gives the following subspecific characters : "Resembling Dendroica 

 aestiva aestiva^ from which it differs in smaller size, paler (or less 

 brightly yellow) coloration, and, in the male, narrower streaking on 

 under surface; differs from Dendroica aestiva ruhiginosa in much 

 smaller size and yellower coloration, and from Dendroica aestiva 

 sonorana in smaller size and much darker coloration." 



Spring. — Both imbiginosa and hrewsteri occur in California and in 

 Washington on migrations. As it is difficult to distinguish the two 

 forms in life, some of the following remarks may refer to either or both 

 of these two subspecies. Mrs. Amelia S. Allen writes to me that this 

 species "is the lat^t of the warblers to arrive in the San Francisco Bay 

 region for the breeding season. Sometimes they are here by April 8, 

 but the average date is about April 18. At Lake Tahoe, the first week 

 of June, breeding pairs were settled in the willows and migrants on 

 their way farther north were migrating through." 



Samuel F. Rathbun says in his Washington notes : "Our experience 

 with this species, based on many years of observation, is that the birds 

 in the spring migration progress northward in a series of what may be 

 called waves. Invariably the first noted will be one or two individuals, 

 and these are heard for a short time only and evidently move on. 

 Then there is a break of a day or so before the next are heard, a larger 

 number. A period of a day, or perhaps two or three, may again elapse 

 before the main body of birds arrive and they are heard on all sides. 



