226 



BIRDS OF THE REPUBLIC OF PANAMA PART 4 



ragua are more closely allied to northern gilvus than to the forms from 

 Costa Rica south. 



Little is known of the biology of any of the southern races. Slud 

 (Bull. Amer. Mus. Nat. Hist., 1964, vol. 128, p. 312), writing of V. 

 gilvus chiriquensis, the bird of Costa Rica and western Panama, says it 

 generally occurs in small groups, in two's, or singly, high in trees or 

 lower in second growth and thickets. Like other vireos it is a persistent 

 singer. Eisenmann (Condor, 1962, p. 505-506) found the song like 

 that of a northern Warbling Vireo, but shorter and less varied, with 

 song phrases lasting 3 to 3.5 seconds and pauses in between of 3 to 

 5 seconds. Other vocalizations include a high thin tsip, sometimes 

 dzheep; a tsip, tit-tit-tit-tit, given when moving about; and a sharp 

 zweeyoo, zweeyoo, sweeyoo, given when gleaning, often hanging up- 

 side down. 



Eisenmann {op. cit.) believes that V. gilvus has increased in Pan- 

 ama with the clearing of forest. 



VIREO GILVUS CHIRIQUENSIS (Bangs) 



Vireosylva josephae chiriquensis Bangs, 1903, Proc. New England Zool. Club., 4, 

 p. 9. (Boquete, 4000 ft, Volcan de Chiriqui, Panama.) 



Characters. — Back light grayish olive, contrasting with olive-brown 

 crown; undersurface decidedly yellow. 



Measurements. — Males (10 from Chiriqui), wing 59.5-67.5 (64.0), 

 tail 43.3-49.6 (45.9), culmen from base 10.4-12.6 (11.6), tarsus 15.3- 

 17.3 (16.5) mm. 



Females (10 from Chiriqui), wing 59.0-66.0 (62.0), tail 40.7-47.5 

 (45.0), culmen from base 10.9-12.5 (11.9, average of 9), tarsus 15.4- 

 17.6 (17.0) mm. 



Resident. Common in forest borders, open woodland, and shrubby 

 clearings in the highlands of western Panama, and in Costa Rica. 

 Griscom (Bull. Mus. Comp. Zool., vol. 78, 1935, p. 364) gives its range 

 in Panama as "mountains of Chiriqui and Veraguas." Ridgely (1976, 

 p. 286) includes western Bocas del Toro as well. W. W. Brown, Jr. 

 (Bangs, Proc. New England Zool. Club, vol. 3, 1902, p. 58) collected 

 this species at Boquete and on the Caribbean slope of Volcan de Chiri- 

 qui between 1200 and 2100 m. Monniche (Blake, Fieldiana: Zool., vol. 

 36, no. 5, 1958, p. 554) found it on Volcan de Chiriqui between 1560 

 and 1860 m. Ridgely found it at 1150-1200 m at Fortuna, Chiriqui, in 

 1976. Two specimens from Isla Cebaco and 1 from Isla Sevilla (both 

 localities listed by Zimmer, Amer. Mus. Nat. Novit., 1127, 1941, p. 19), 

 were collected by J. H. Batty, whose locality data has been shown to 



