SONORA YELLOW WARBLER 119 



SoNORA Yellow Warbler 



DENDROICA ESTIVA SONORANA Brewsl. 



Subspecific Characters.— Resembles Dendroica eestiva (estiva but adult <? 

 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 $ grayer above and below than adult $ 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 (Ridgiv.). 



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^ 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^) 



Eggs. — 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, .7ox.5r, .70X.50, 

 .68X.52, .69X.S1. 



Biographical References 



(i) O. W. Howard, Summer Resident Warblers of Arizona, BulL Cooper 

 Orn. Club (=Condor), I, 1899, 39. 



Alaskan Yellow Warbler 



DENDROICA /ESTIVA RUBIGINOSA (Pall.) 



SuhspeciHc Characters. — Similar to Dendroica astiva astiva but slightly 

 smaller, adult c? darker above, the crown of nearly the same color as the back, 

 only the forehead yellower ; the rump more nearly the color of the back than 

 in astiva. 



