560 



BIRDS OF THE REPUBLIC OF PANAMA PART 4 



breast, and in ravida belly, black; rest of undersurface grayish green; 

 female, upper surface yellowish green; undersurface dingy white 

 tinged green. 



Description. — Length 88-101 mm. Adult male, superciliary and chin 

 dark yellow; forehead, sides of face to eye, throat, and breast black; in 

 ravida black extends to nape, over entire side of head, and to belly; rest 

 of upper surface, including wing coverts and tail, olive-green in T. o. 

 pusilla, darker in ravida; remiges dusky, edged green of upper surface; 

 remainder of undersurface grayish, tinged green of upper surface; 

 bend of wing pale yellow. 



Adult female, entire upper surface, including wing coverts and tail 

 olive-green; remiges dusky, edged olive-green; undersurface dingy 

 olive, whiter in center of belly; faint superciliary and patch on chin of 

 buff-yellow. 



The Yellow- faced Grassquit is very common in pastures, clearings, 

 and other grassy areas in the foothills and highlands of both slopes to 

 around 1800 m, but is scarce and local in the lowlands. The only island 

 off Panama on which it has been collected is Coiba, where a well-marked 

 race, ravida, is common. The mainland race, pusilla, ranges from Mexi- 

 co through Central America to Colombia and western Venezuela; 

 other forms are found on islands in the Greater Antilles. 



This species feeds almost exclusively on the seeds of various grasses. 

 One collected by E. A. Goldman at Lion Hill, Canal Zone, held 10 seeds 

 of Paspalum sp. and about 40 seeds of Panicum sp. Skutch (Pac. 

 Coast Avif., no. 31, 1954, p. 38) has seen them forage in the crowns of 

 low trees, almost in the manner of warblers, when grass seeds are 

 scarce. When feeding on grass seeds, they often perch on the stem of 

 the plant on which they are feeding, or on an adjacent stem, and some- 

 times use their feet to hold the tip of the blade more conveniently. 

 Two males collected by Strauch (Bull. Brit. Orn. Club, 1977, p. 65) 

 weighed 9.3 and 10.3 g. Grassquits usually feed in flocks, often with 

 other species including Blue-black Grassquits {Geospiza jacarina), 

 Variable Seedeaters (Sporophila americana) , and White-collared Seed- 

 eaters (S. torqueola) . When they fly up from the ground, however, I 

 have noticed that they maintain close flock association in the bushes in 

 which they take refuge, quite different from the straggling of seedeaters 

 and Blue-black Grassquits when flushed. At the end of the dry season, 

 when grassquits are forming pairs, they spend less time in flocks (Fair- 

 child et al., Ibis, 1977, p. 87). 



The song of this species is a long, weak trill delivered from a low 



