SONORA YELLOW WARBLER 189 



According to the 1931 Check-List, the California yellow warbler 

 "migrates through eastern California, Arizona, and Lower California; 

 winters sparsely in the Cape District of Lower California and south 

 to Guatemala, Nicaragua, and Costa Rica." 



Winter. — Dickey and van Eossem (1938) record this warbler as a 

 "winter visitant and spring migrant in the Arid Lower Tropical 

 Zone," in El Salvador. "The small Pacific coast race, brewsterii^ is 

 apparently relatively the least common of the four forms found in El 

 Salvador; at any rate, the small number of specimens taken indicates 

 that this is the case. Yellow warblers were common in January at 

 Puerto del Triunfo and in February at Rio San Miguel, but unfortu- 

 nately only one specimen was taken at each place. Whether all of 

 these winter birds were hrewsteri and morcomi is problematical." 



DENDROICA PETECHIA SONORANA Brewster 



SONORA YELLOW WARBLER 



HABITS 



This is the palest of all the yellow warblers, one of the many pale 

 races of the southwestern desert regions. Its breeding range extends 

 from southeastern California, southern Utah, Arizona, and New 

 Mexico to central western Texas, Sonora, and Chihuahua; and it 

 winters from Mexico southward to Guatemala, Nicaragua, and Costa 

 Rica. 



It is best described by Ridgway (1902) as "similar to D. (B. aestiva, 

 but much paler; adult male lighter and much more yellowish olive- 

 green above, the back frequently (usually?) streaked with chestnut, 

 pileum usually wholly clear yellow, lower rump and upper tail-coverts 

 yellow, faintly streaked with olive-greenish ; wing edgings all yellow ; 

 under parts lighter yellow than in D. ce. aestiva^ and with chest and 

 sides much more narrowly (often faintly) streaked with chestnut; 

 adult female conspicuously paler than in D. ce. aestiva, the upper 

 parts often largely pale grayish, the under parts usually very pale 

 buflfy yellow." 



Woodbury, Cottam, and Sugden (MS.) say of its status in southern 

 Utah: "This race of yellow warbler is a breeder of the streamside 

 fringes of willows, tamarix, and brush of various kinds along the San 

 Juan and lower Colorado Rivers. It undoubtedly extends up the 

 Colorado above the mouth of the San Juan, but how far it extends 

 before yielding to morcomi has not been determined. Data available 

 are not sufficient to determine its nesting or migration dates or the 

 length of its stay in Utah." 



Swarth (1914) calls it "a common summer visitant in southern and 

 western Arizona, apparently confined almost entirely to the Lower 



