562 



BIRDS OF THE REPUBLIC OF PANAMA PART 4 



or globular structure of thickly interwoven grasses, lined at the bottom 

 with finer fibers with an entrance on the side. One nest was 14 cm 

 high and 7.5 cm in transverse diameter. Two to four eggs form the 

 clutch, with two being the most common. The eggs are dull white, 

 speckled with shades of brown and chocolate, thickly on the large end 

 and sparingly over the rest of the surface. The measurements of 10 

 eggs averaged 16.8x12.8 mm. Incubation is performed only by the 

 female, and requires 12 to 16 days. 



Both parents feed the nestlings regurgitated bits of grass seeds. At 

 hatching, the young have nearly black skin and no down; the mouth 

 lining is red. At 3 days, their eyes begin to open and at 8 days the 

 plumage is fairly developed. By 10 days, they are well feathered. 

 When the young leave the nest at 12 to 13 days, they are completely 

 feathered, in a plumage like the female's. At the end of the nesting 

 season, adults and young form joint flocks. 



TIARIS OLIVACEA RAVIDA Wetmore 



Tiaris olivacea ravida Wetmore, 1957, Smiths. Misc. Coll., 134 (9), p. 100. (Isla 

 Coiba, Panama.) 



Characters. — Male, black extends to nape, entire side of head, and to 

 belly; green of upper surface darker; female grayer green throughout. 



Measurements. — Males (7 from Isla Coiba, including the type), 

 wing 50.2-53.9 (52.6), tail 38.7-40.9 (39.8), culmen from base 10.2- 

 11.3 (10.6, average of 6), tarsus 15.9-18.0 (17.1) mm. 



Females (5 from Isla Coiba), wing 50.7-52.0 (51.6), tail 37.0-38.1 

 (37.6), culmen from base 10.4-11.2 (10.7), tarsus 16.2-17.7 (17.0) 

 mm. 



Resident. Found only on Coiba Island, where during my visit in 

 1956 it was common along the borders of the pastures and at the edge 

 of the forest, congregating especially where tall grasses bore ripening 

 seeds. At headquarters, dozens came to feed about the mill that hulled 

 the rice, and in the remote work camps, where rice was pounded by 

 hand, the grassquits gleaned the fallen grain about the kitchens. They 

 were completely tame, and often came hopping about the feet of men 

 sitting on the benches at guard headquarters. Fully grown young were 

 common, and on January 14 adults were mating; on the mainland I 

 have never seen any sign of breeding at this time of year. 



The dark color of these birds was noticeable even in life. The sub- 

 specific name is from the Latin ravidus, grayish. 



