356 



BIRDS OF THE REPUBLIC OF PANAMA PART 4 



had the iris light reddish brown; bill, tarsus, toes, and claws black. A 

 female collected there that day was the same except for the iris, which 

 was light mouse brown. At death, the reddish color of the iris changes 

 within seconds to orange and then pale straw yellow (Olson, Proc. 

 Wash. Biol. Soc, vol. 86, no. 34, 1973, p. 408) . 



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

 169.9-204.5 (191.1), tail 129.5-157.0 (145.4), culmen from base 35.9- 

 39.9 (37.5), tarsus 41.7-48.0 (44.5) mm. 



Females (10 from Panama and Colombia), wing 145.5-167.0 

 (155.2), tail 112.5-133.0 (119.2), culmen from base 31.3-33.5 (32.7), 

 tarsus 37.2-39.9 (38.8) mm. 



Figure 29. — Giant Cowbird, Vaquero Gigante, Scaphidura oryzivora, male. 



Resident. Uncommon but widespread in lowlands of both slopes, 

 except in the drier areas; it is absent from the eastern side of the 

 Azuero Peninsula, southern Code, and most of western Province of 

 Panama. In July 1975 and March 1981, Ridgely {in lift.) found this 

 species more numerous in the Tuira lowlands of Darien than anywhere 

 else in Panama. In July they were in flocks of well over 100 birds; in 

 March, the breeding season, the birds were more dispersed, but equally 

 abundant. This species parasitizes oropendolas and the colonial caci- 

 ques, so during their nesting season is found in the same areas; at other 

 times it is dispersed over more open country, generally feeding and dis- 

 playing on the ground. 



The Giant Cowbird is found from southern Mexico to southeastern 

 Brazil and northeastern Argentina. Peters (Proc. Biol. Soc. Wash., 



