600 BIRDS OF THE REPUBLIC OF PANAMA PART 4 



blackish brown, with outer webs edged color of back; throat white; 

 sides of flanks gray, sometimes becoming olive-green; rest of under- 

 surface white; underwing coverts olive-green. 



Adult female, like male, but with lower border of pectoral band gray 

 and crown colors duller. 



Juvenile, entirely olive-green, tinged buffy on throat and belly. 



The Orange-billed Sparrow is an unobtrusive resident of the thick 

 undergrowth in humid forest and second growth in the lowlands and 

 foothills of both slopes, ranging up to about 1200 m. It is widespread 

 and fairly common. Three races have been recognized in Panama — 

 rufidorsalis of the Almirante Bay region of Bocas del Toro and the 

 Caribbean slope north to Honduras, nominate aurantiirostris of Pacific 

 slope Costa Rica and western Panama, where, from at least El Uracillo, 

 Code, it inhabits the Caribbean as well as the Pacific slope as far east 

 as the Canal Zone area, and strict ocollaris, found from the Canal Zone, 

 where it mixes with the nominate form, to Darien and San Bias and 

 adjacent northwestern Colombia. Three birds I collected in eastern 

 Province of Panama at Cerro Chucanti and 1 from Cerro Azul seem 

 intermediate between strict ocollaris and nominate aurantiirostris, but 

 closer to strict ocollaris. The distinctions between the 2 latter races 

 found in Panama are rather fine. Olson's analysis (Bull. Brit. Orn. 

 Club, 1983, vol. 103, no. 2, pp. 84-86) is followed here. A. a. aurantii- 

 rostris is the form west of the Canal Zone and strict ocollaris east of the 

 Canal Zone, with specimens of both occurring in the Canal Zone, the 

 only exception being 2 (of 3) specimens from Mandinga, San Bias, 

 that appear to be more typical of aurantiirostris. Other races range 

 from southeastern Mexico to northern Peru and Ecuador. 



This species feeds almost entirely on the ground and rarely rises 

 more than 3 m from the forest floor even to sing. It is usually in pairs 

 or family groups. The stomach of 1 collected by E. A. Goldman at 

 Porto Bello, Canal Zone, on May 25, 1911, contained fine fragments of 

 ants of two species 50%, fragments of seeds of Oxalidaceae 15%, bits 

 of seeds of Solanaceae 15%, other ground-up vegetable matter 20%. 

 One that I collected at El Cope, Code, contained a long-antennaed 

 cricket. At Jaque, Darien, I saw 1 near antbirds, but I could not be 

 sure if it was accompanying them. Ridgely {in litt.) saw 1 attending 

 an ant swarm at least briefly on April 27, 1980, in the Rio Changuinola 

 Valley (200 m), Bocas del Toro. Four collected by Burton (Bull. Brit. 

 Orn. Club, 1975, p. 86) weighed from 29 to 33 g. The song of the male 

 is a series of rising and falling metallic notes; both sexes also have a 

 chipping note. 



