572 BIRDS OF THE REPUBLIC OF PANAMA PART 4 



bill darker than in the dry season, the maxilla being horn color, mandi- 

 ble plumbeous; gape yellowish. A female taken that day had the bill 

 fuscous or horn color, like the mandible of male. An immature male 

 collected at Chiva Chiva, Canal Zone, on January 11, 1955, had the bill 

 darker than do birds in the breeding stage; it was dark neutral gray. 



Measurements. — Males (10 from Panama and Colombia), wing 

 52.5-57.5 (55.0), tail 42.1-47.7 (44.1), oilmen from base 9.2-10.2 

 (9.6), tarsus 13.1-14.7 (14.1) mm. 



Females (6 from Panama and Colombia), wing 50.0-54.0 (52.0), 

 tail 41.2-44.8 (42.6), oilmen from base 8.2-10.1 (9.5), tarsus 13.2-14.6 

 (13.8) mm. 



Resident. Common on the entire Pacific slope, mainly in the low- 

 lands, but in small numbers up to about 1800 m; on the Caribbean 

 slope it is found only in the Canal Zone area. W. W. Brown, Jr., col- 

 lected 2 on Saboga Island in the Pearl Islands archipelago in April 

 1904. Beyond Panama, this race ranges from southern Costa Rica 

 south through northern, central, and eastern South America to Bolivia, 

 southern Brazil, and northern Argentina, and on some islands off the 

 coast of Venezuela, including Trinidad, Tobago, and Grenada. 



Like other seedeaters, this species feeds extensively on grass seeds 

 and inhabits grassy and shrubby areas. It perches regularly in low 

 trees and sings from them. Among the preferred plant foods is Guinea 

 grass (Panicum maximum Jacq.) , an introduced African species widely 

 cultivated as a forage grass. A male collected by Strauch (Bull. Brit. 

 Orn. Club, 1977, p. 65) weighed 9.9 g. 



When not nesting, the Yellow-bellied Seedeater usually is found in 

 flocks; during the dry season it vacates many areas on the Pacific slope 

 for more humid ones on the Caribbean side of the Canal Zone area. 

 Ridgely (in litt.) has seen close to 1000 near French Canal on Ft. 

 Sherman, Canal Zone, on May 1, 1976. 



The male's song is sweet, but ends with two buzzy phrases, seewee- 

 seewee-seewee-seewee-soosoo, bzeewee-bzeewee (Eisenmann, Smiths. 

 Misc. Coll., vol. 117, no. 5, 1952, p. 58) . Both sexes also have a variety 

 of short and scolding notes. 



In South Gamboa, on the Caribbean side of the Canal Zone, Cora C. 

 Alderton (Condor, 1961, pp. 390-398) found that during the years 

 1956-1959 this species would appear in April or June and remain until 

 October or December. Males did not begin singing until several weeks 

 after they arrive, and nest construction may not begin for several more 

 weeks. The nest is built by both sexes; it is a cup woven of grasses and 



