1228 U.S. NATIONAL MUSEUM BULLETIN 23 7 part 2 



The upper mandible was gray on the anterior half; the mouth was 

 bright red and the rictal flanges yellow." The natal down is replaced 

 by the heavily streaked juvenal plumage, which G. M. Sutton (1935) 

 describes as follows: 



* * * In general appearance the eight to ten day old birds are more streaked 

 than are older birds, especially on the crown and chest. By the time the juvenal 

 plumage is fully unsheathed there is practically no streaking on the crown and 

 hind neck, and the streaks of the underparts have much the appearance of spots 

 or flecks. The postjuvenal molt begins when the individual is about sixteen days 

 old, toward the end of June or early in July in young of the first brood. This molt 

 involves only the body plumage (including the wing coverts) as a rule, though 

 Dwight tells us that "the middle pair of rectrices is occasionally renewed." 



* * * Four specimens at hand, all with fully developed juvenal flight feathers 

 (July 14 to 30), are in various stages of the postjuvenal molt, the back in every 

 case having two distinct types of feathers: the comparatively dull, buffy-edged, 

 loose, plumulaceous type characteristic of the juvenal plumage in all Fringillidae ; 

 and the sleek, firm, red-brown type that is characteristic either of this species' 

 first winter plumage or of some intermediate, postjuvenal plumage. The specimen 

 taken July 30 (U.M.M.Z. No. 75012), is naturally the brightest of these, about 

 a dozen new red-brown feathers showing plainly in the back. 



In a series of 15 juvenal field sparrows Sutton found a considerable 

 variation in the amount of streaking below. Not one of his Michigan 

 specimens showed any streaking on the throat as Dwight (190C) 

 mentions. 



Of the first fall and winter plimaage T. S. Roberts (1932) notes. 

 "The stripes on underparts are lost at the postjuvenal molt and the 

 young closely resembles the adult, which, in the fall and winter dress, 

 are more rusty and buffy than in the spring and summer plmnage." 

 The breeding adult plumage which, as Dwdght noted, is acquired 

 largely by wear, Roberts goes on to describe thusly: 



Crown and nape rusty-brown with a more or less evident median gray stripe; 

 sides of head gray with a rusty-brown stripe back of eye and a small spot in front 

 of eye; an indistinct buflfy eye-ring; back and scapulars rusty-brown, streaked 

 with black, rufous, and buff; rump and upper tail-coverts light grayish-brown, 

 lightly if at all streaked; below grayish-buff on breast and sides, paler on throat, 

 and shading behind into white or grayish-white on abdomen, belly, and under 

 tail-coverts; wings dusky, primaries narrowly edged with light, secondaries and 

 tertiaries more broadly with rufous; coverts dark centrally, edged with rufous, 

 and the middle and greater tipped with white or buffy-white, forming two more 

 or less conspicuous wing-bars; tail grayish-brown, outer feathers narrowly edged 

 with white. Bill pinkish ; legs and feet pale flesh color, darker on feet ; iris brown. 



Food. — In his classic work, Judd (1901) notes that the field sparrow 

 eats about 41 percent animal and 59 percent vegetable matter. The 

 animal food consists of weevils, beetles (May, click, leaf, ground, and 

 tiger), grasshoppers, caterpillars, leafhoppers, ants, flies, wasps, and 

 spiders. The vegetable matter is made up of grass seeds (crab, 

 pigeon, broomsedge), chickweed, purslane, lamb's quarters, gromwell, 

 knot-weed, wood-sorrel, with some oats after harvesting time. 



