1238 U.S. NATIONAL MUSEUM BULLETIN 23 7 pabt 2 



the trill — I " ' ' ' ■ ' or pee chrrrrrr. The entire peee is usually pitched 

 lower than the triU, but one bird sang the initial phrase several tones 

 higher than the triU which followed. Most birds sang the initial 

 phrase softer, with less carrying power than the trill. As compared 

 with the field sparrow, the middle notes are lacking and there is no 

 gradual accelerando. 



Nest. — The nest of the species is unknown save for the several 

 Brown collected at Miquihuana, Tamaulipas, in 1924. Brown (in 

 Thayer, 1925) describes the nest as "well made, compact, and well 

 concealed. It is constructed of rootlets and grasses and lined with 

 fine fibers and sometimes with horsehair and is placed without excep- 

 tion within six inches of the ground. Sometimes it even rests upon 

 the ground like a Song Sparrow's nest, but supported by the weed in 

 which it is built." 



Charles H. Blake, who kindly examined for me the 27 nests com- 

 plete with eggs in the Thayer Collection at Harvard writes: "In 

 dimensions and wall construction I doubt that the nests could be 

 told from those of field sparrows. The lining is a little more like that 

 used by the chipping sparrow, mostly composed of very fine rootlets. 

 Some nests include a few long, black hairs. The external diameter 

 runs from 75 to 95, mostly about 80 to 85 miUimeters. The internal 

 diameter is 45 to 50, and the depth 25 to 35, mostly 30 to 35 milli- 

 meters. The smallest nests are about 65 millimeters in external 

 diameter, but without reduction of the internal diameter." 



Eggs. — Worthen's sparrow usually lays three or four eggs. They 

 are ovate with some tending toward elongate ovate, and are slightly 

 glossy. The "bluish glaucous" or "Etain blue" ground is speckled, 

 spotted, and occasionally blotched with "natal brown," "snuff 

 brown," "Mars' brown," or "Brussels brown." The majority of 

 eggs do not seem to have undermarkings, but when present these are 

 "light neutral gray." The spottings, either sharply defined or some- 

 what cloudy, are generally concentrated toward the large end. The 

 measurements of 50 eggs average 18.1 by 13.4 millimeters; the eggs 

 showing the four extremes measure 19.7 by 13.9, 17.9 by 14-5, 16.2 

 by 13.1, and 18.3 by 12.1 millimeters. 



Field marks. — ^A slender, clear-breasted sparrow with a pink bill 

 and a white eye ring. Persons from the eastern United States wiU 

 note the resemblance to the field sparrow; the differences are the 

 grayer, more ashy shade of the back, the lack of the brown postocular 

 stripe, and the presence of the eye ring in the Worthen's sparrow. 

 Adult males are marked, in addition, by a prominent gray nape, or 

 coUar, and a gray forehead, rather sharply setting off the chestnut 

 pUeum. 



