SOUTHERN SWAMP SPARROW 1481 



neck are assumed, and a nearly complete renewal is indicated in some 

 cases judging by the freshness of the feather borders." Many adults 

 of both sexes lack the reddish brown cap in the spring and have the 

 entire top of the head striped with black and reddish brown with a 

 median gray stripe as in winter plumage. This may represent a 

 first-year nuptial plumage. 



The adult winter plumage according to Dwight is "acquired by a 

 complete postnuptial moult in August and September. Practically 

 indistinguishable in many cases from first winter, but usually with 

 more chestnut on the crown, the superciliary line and sides of neck a 

 clearer darker gray, the chin not yellow tinged but white and a grayer 

 cast of plumage everywhere perceptible." 



Mean body weights are given in grams as 17.61 (Wetherbee, 1934), 

 15.88 (Stewart, 1937), and 18.5 ±2.49 (Hartman, 1946). G. B. Becker 

 and J. W. Stack (1944) give the average temperature of two birds as 

 110.2° F. 



Food. — The swamp sparrow is the most highly insectivorous species 

 in its genus. This is reflected in the reduced size of its skull and bill 

 and bulk of jaw muscle in comparison to those of the seed-cracking 

 song sparrow (Beecher, 1951). Banders note its absence from grain- 

 baited traps during the nesting season (Commons, 1938). Martin, 

 Zirn, and Nelson (1951) show its diet to be 55 percent insects in winter, 

 88 percent in spring and early summer. "Beetles, ants and other 

 Hymentoptera, caterpillars, grasshoppers, and crickets appeared most 

 commonly as items in the insect part of the diet." In late summer and 

 fall the diet becomes 84 percent to 97 percent granivorous, with 

 seeds of sedges, smartweed, panicgrass, and vervain heading the list. 

 Sylvester D. Judd (1901) writes: "[It] takes more seeds of polygonums 

 than most birds, and eats largely of the seeds of the sedges and aquatic 

 panicums that abound in its swampy habitat. The giant ragweed 

 (Ambrosia trijida) is also well represented in its stomach contents." 



Thomas Nuttall (1840) noted it ate "the smaller coleopterous kinds" 

 of insects, as did I in my examination of nestling stomachs. The 

 ready recognizableness and relative indestructibility of the chitinous 

 remains of Carabid and Curculionid beetles perhaps biases uncritical 

 examinations. Forbush (1929) credits this species with "control 

 over the increase of such marsh insects as the army worm." C. C. 

 Abbott (1895) describes the birds picking at dead drying herring, 

 and A. H. Howell (1932") mentions their coming to bread crumbs at 

 one of his camps in Florida. 



Voice. — F. H. Forbush (1929) describes the swamp sparrows voice 

 as: "Call note a clink, chip or cheep, with a metallic ring; song 

 weet-weet-weet-weet-iveet, etc., a little like that of Chipping Sparrow, 

 but less dry, louder, a trifle more musical and more varied; also a 



046-737—68 — pt. 3 16 



