GRAY VIREO 273 



and 12 females, all of which except one were taken between April 1 

 and June 11, "They present very little variation in size or color, and 

 the young in first plumage do not differ materially from the adult 

 birds." 



Frank Stephens (1890) considers the California birds different 

 from those east of tlie Colorado River in breeding area. He says : "The 

 most prominent difference betw^een the two forms is the darker color 

 above, combined with the greater amount of whitish edging on wing 

 and tail, in the California form." 



Grinnell (1922) collected a male out of a pair at Walker Pass, Kern 

 County, Calif., on July 25, 1922. He says that the bird "proved to be 

 in molt, with only two of the old tail-feathers remaining and with new 

 feathers showing where old ones had fallen out, in the wings and in 

 most of the body tracts. The weight of the bird was 12.5 grams." 



Grimiell and Swarth (1913) describe an adult male secured on Au- 

 gust 27 as being in nearly full fresh fall plumage. "The annual molt 

 is very nearly completed, only the outermost primaries being still 

 partly unsheathed." They say furtlier: 



Since there is in all probability no spring molt, even partial, this bird presents 

 the true color characters of the species. As compared with the better known 

 spring plumage, conspicuous among various species of the family for its general 

 plumbeous tone, the freshly acquired plumage is not so distinctly gray save about 

 the head. The whole dorsum, the outer surface of closed wing, and, more ap- 

 preciably, the rump and upper tail coverts, are pervaded with a tinge of green; 

 the sides and flanks have a conspicuous tinge or mixture of primrose yellow; 

 and there is a faint buffy suffusion across the chest. All these tints are evidently 

 vei-y much reduced, or obliterated altogether, through the intervening months 

 of wear and fading, until spring brings the notable gray cast again. 



With more material than had been available to Frank Stephens, they 

 came to the conclusion there was no basis for systematic separation of 

 the California birds from the Arizona ones. They conclude, in this 

 respect, as follows : "From a consideration of its distribution as now 

 known, it appears probable that the gray vireo has invaded California 

 from the south-central plateau region of western North America, 

 within relatively recent times." 



Food. — Frank Stephens (1878) comments as follows: "I have never 

 seen them catching insects in tlie air, as some other Vireos do, but have 

 observed them scratching on the ground like a Pipilo." 



From the only two stomachs examined by the Biological Survey, Dr. 

 Edward A. Chapin (1925) could obtain only a hint as to the food of 

 the gray vireo: "Caterpillars and a small moth were found in one 

 stomach, together with a stink-bug {Prionosoma fodoinoides) , a tree 

 hopper {Platycenf/rus acuticornis), and a tree cricket {Oecanthus). 

 In the other stomach two dobson flies (Chaidiodes), a small cicada 

 {Tibicinoides hesperius) , and a long-horned grasshopper made up the 



