FAMILY CUCULIDAE III 



lected at Perme, San Bias, October 16, 1929, by H. von Wedel. 

 Horace Loftin recorded 2 near Almirante, Bocas del Toro, October 

 10, 1963. A specimen in the Gorgas Memorial Laboratory was taken 

 there on October 3, 1964. 



It is probable that the species passes more regularly through the 

 Isthmus than the few reports indicate. It ranges in the cover of 

 leaves in trees and higher stands of shrubbery, and as it moves 

 quietly it readily escapes detection. This is particularly true during 

 its migrations as then it is silent, while on its northern nesting grounds 

 attention is drawn to it most often by its slowly uttered calls. 



COCCYZUS AMERICANUS (Linnaeus): Yellow-billed Cuckoo; 

 Cuclillo Piqui-amarillo 



Lower mandible, except for black tip, and base of maxilla bright 

 yellow; tail feathers tipped broadly with white; slight rufous band 

 on side of wing. 



Description. — Length 270-290 mm. Adult (sexes alike), above 

 grayish brown, with a faint sheen of bronze on wings and tail; 

 auricular region faintly darker; loral area dull gray; outer webs 

 of some of the proximal primaries dull rufous, forming an indistinct 

 band along the center of the wing ; tail much graduated ; central tail 

 feathers blackish at tip ; others dull black, tipped broadly with white ; 

 outer web of outermost, in addition, white ; entire under surface, 

 including malar region, dull white ; breast and lower foreneck tinged 

 faintly with gray ; abdomen in some faintly buff ; under wing coverts 

 white to buffy white ; under side of wing with inner web of primaries, 

 except the outer one, cinnamon-rufous at center. 



Immature, tail with outer feathers duller black; light terminal 

 area less clearly marked, usually reduced in extent, and grayish white. 



This is another migrant from the north that crosses through the 

 Isthmus en route to wintering grounds in South America. The birds 

 range in thickets and forest, where they move quietly, often resting 

 motionless for several minutes, except for the peering head. As they 

 are plainly colored and of slender form they remain so hidden that 

 they are seen only casually. 



They pass southward mainly in September and October, and north- 

 ward principally in April. Both eastern and western races are known 

 from the Isthmus as will be indicated in the sections on these sub- 

 species that follow. The usual criterion for separation of these two 



