566 



BIRDS OF THE REPUBLIC OF PANAMA PART 4 



rarely, three eggs are laid. They are pale blue, bluish-white, or pearl- 

 gray, finely mottled with light brown or chocolate, occasionally more 

 heavily blotched with black or deep brown. Measurements average 

 16.3 X 12.7 mm. Incubation requires 13 days and is performed entirely 

 by the female. Both parents feed the young, which remain in the nest 

 10 or 11 days. As the breeding season is so long, each pair of birds may 

 nest more than once. 



SPOROPHILA AMERICANA (Gmelin): Variable Seedeater, 

 Arrocero Piquigordo 



Figure 46 



Loxia americana Gmelin, 1789, Syst. Nat., 1(2), p. 863. (Cayenne.) 



Small; male variable, from nearly entirely black, with white spec- 

 ulum, to black with extensive white on throat, underparts, and rump. 

 Female mostly olive-brown. 



Description. — Length 98-105 mm. Adult male, variable, from nearly 

 entirely black with white speculum, midline of belly, and underwing co- 

 verts, to extensively marked with white on throat, sides of nape, under- 

 surface below black breast band, rump, speculum, and underwing 

 coverts. 



Female, mostly olive-brown, becoming lighter on sides of head, 

 throat, and center of belly. 



The Variable Seedeater is abundant throughout Panama in clearings, 

 gardens, and open country. It is commonest in the lowlands. Usually 

 it occurs in small flocks in which females and immatures outnumber 

 the adult males. Although most often found in thickets and grasses, 

 these birds occasionally perch in the tops of fairly tall trees. Eisenmann 

 (Smiths. Misc. Coll., vol. 117, no. 5, 1952, p. 58) describes the song as 

 "A sweet, rapid, twittering, somewhat canarylike tsiwee tsiwee tsiwee, 

 chee chee chee, twee-twee-twee-twee, chirr chirr chirr chirr with vari- 

 ations; the chirrs often omitted. The call is a sweet questioning chiwee 

 or tsiwee; also cheep" 



This species feeds almost entirely on grass seeds. Of 7 stomachs 

 examined by E. A. Goldman, only 1 contained any animal matter, a bit 

 of a hymenopteran. Plant matter included seeds of Solanum, Paspalum, 

 Amaranthus, Panicum, Sp or bolus, Car ex, and Chaetochloa. I have 

 often seen them fly up to a seed-bearing grass stem and land so that it 

 bent to the ground where the seeds could more easily be picked off. At 

 Juan Mina, Canal Zone, I once saw a number of these birds feed on 

 grass heads growing in water well out from land. Strauch (Bull. Brit. 



