2l8 



BIRDS OF THE REPUBLIC OF PANAMA PART 4 



Description. — Adult (sexes alike), crown medium gray, sometimes 

 with indistinct dusky margin; light gray superciliary; lores dull gray; 

 rest of upper surface bright olive-green; sides of breast and flanks olive- 

 yellow; undertail coverts bright sulphur or light lemon yellow; rest of 

 undersurface white; edge of wing and underwing coverts bright sul- 

 phur yellow. 



Juvenile, crown cinnamon-buff; whitish superciliary; rest of upper 

 surface mainly olive-green; throat white; rest of undersurface very 

 pale yellow. 



A breeding male collected March 22, 1961, at La Jagua, Province of 

 Panama, had the iris light reddish brown; maxilla fuscous-brown; 

 mandible dull ivory flesh color; tarsus and toes neutral gray. A female 

 taken May 21, 1953, at Sona, Veraguas, had the iris light brownish 

 orange; maxilla horn color; mandible light neutral gray; tarsus and 

 toes dull neutral gray. The lighter iris seems definitely to be a sexual 

 characteristic. 



Measurements. — Males (10 from Panama), wing 73.6-78.8 (76.7), 

 tail 53.9-59.9 (56.7), culmen from base 14.2-16.3 (15.4), tarsus 16.9- 

 18.1 (17.6) mm. 



Females (10 from Panama), wing 69.0-75.9 (71.7), tail 46.5-53.1 

 (49.5), culmen from base 13.0-15.2 (14.5), tarsus 17.1-18.6 (17.8) 

 mm. 



Resident. Common to abundant in woodland borders, clearings, cut- 

 over areas, coastal scrub and mangroves, gardens, open woods, and 

 second growth on the Pacific slope and on islands off the coast and in 

 extensively cleared areas of the Canal Zone to the Caribbean slope. The 

 Yellow-green Vireo is a widespread breeder on the entire Pacific slope 

 of the Republic, except in Darien, where its status is uncertain (pos- 

 sibly only a transient). At higher elevations and humid lowlands it 

 occurs only in cleared areas: W. W. Brown, Jr. (Bangs, Proc. New 

 England Zool. Club, vol. 3, 1902, p. 58) collected 4 at Boquete (1440 

 m), and Blake (Fieldiana: Zool., vol. 36, no. 5, 1958, p. 553) records 

 it from three localities around the Volcan de Chiriqui at 1560 to 1620 

 m. In the western Azuero Peninsula, Aldrich and Bole (Scient. Publ. 

 Cleveland Mus. Nat. Hist., vol. 7, 1937, p. 117) found it as high as 

 900 m. Off the coast, the Yellow-green Vireo is very common on Isla 

 Coiba and the Pearl Islands. On the Caribbean slope this species rarely 

 appears away from cleared areas in the Canal Zone. Griscom (Bull. 

 Mus. Comp. Zool., vol. 72, 1932, p. 366) notes a female taken by von 

 Wedel on September 3, 1929, at Perme, San Bias, and Peters (Bull. 

 Mus. Comp. Zool., vol. 71, 1931, p. 333) records another Wedel sped- 



