SONORA YELLOW WARBLER 119 



Oberlin, O., May i-June 1 (Jones) ; Jasper Co., la., May 16 

 (C. W. C.) ; Boulder, Colo., June 5 (C. W. C.) ; Denver, Colo., June 

 C (Dille) ; San Jose, Calif., April 5 (C. W. C.) ; Tacoma, Wash., May 

 24- June 17 (Bowles) ; Ann Arbor, Mich., May 5, Ypsilanti, Mich., 

 June 23 (Wood). 



Biographical References 



(1) C. J. Morrison, Yellow Warbler vs. Cowbird. Orn. and 061., IX, 

 1884, 124. (2) J. P. N. [orris], Eggs of the Western Yellow (=Yellow) 

 Warbler, Orn. and 061., XII, 1887, 185. (3) A. B. Dunning, Yellow Warbler 

 (in E. Mass.), Oologist, IX, 1892, 35. (4) N. F. Posson, Incessancy of the 

 Yellow Warbler's Song, Ibid., IX, 1892, 65. (s) Morris Gibbs, The Blossom- 

 Eater, Nidologist, II, 1894, 48. 



Sonora Yellow Warbler 



DENDROICA .ESTIVA SONORANA Brewst. 



Subspeci&c Characters. — Resembles Dendroica (estiva astiva but adult d 

 paler above, the back yellower, the feathers usually with dark shaft 

 streaks; the tail with more yellow, all the feathers, including the central pair 

 being yellow at the base on both webs; streaks below finer, less numerous, 

 sometimes barely evident. 



Adult 9 grayer above and below than adult S astiva, the underparts some- 

 times grayish tinged with green. 



General Distribution. — Southwestern United States and north- 

 western Mexico. 



Summer Range. — Western Texas (Frontera, Fort Hancock, 

 etc.,) southern New Mexico, southern Arizona, and southward into 

 northwestern Mexico (Ridgw.). 



Winter Range. — Mexico southward to Nicaragua. 



The Bird and its Haunts. — This southwestern form of the Yellow 

 Warbler resembles the eastern bird in habits and, like it, shows a 

 marked preference for willows. Owing to the aridity of the country 

 in which it lives, suitable haunts are less common than in the east 

 and the bird is proportionately less numerous. 



Nesting Site. — Along the San Pedro River in southern Arizona, 

 Howard 1 found "several nests placed in willow and mesquite trees, 

 generally in upright forks from ten to twenty-five feet up." 



Nest. — "The nests are very much like those of the Yellow War- 

 bler." (Howard 1 .) 



Egg s - — Usually 4. Ground color, in the sets I have examined, 

 has been paler than in eggs of the Yellow Warbler, but the markings 

 are the same. Size; a typical set of four measures, .70X.51, 70X.50, 

 .68X.52, .69X.51. 



