FAMILY VIREONIDAE 



227 



be unreliable (Wetmore, Smiths. Misc. Coll., vol. 134, no. 9, 1957, p. 7) . 

 The specimens almost certainly come from Boquete, as did the re- 

 mainder of Batty's series in the American Museum. The Smithsonian 

 specimens all come from Chiriqui — at Quiel (1560 m) near Boquete, 

 Santa Clara (1260 m), Cerro Punta, and El Volcan (1350 m). 



My own experiences with this vireo have been limited. On March 

 7, 1954, I shot 1 from a little group of migrant warblers in high 

 branches at the border of forest near El Volcan. At other times I have 

 found it in forest undergrowth. Eisenmann (Condor, 1962, p. 505) 

 noted that at Cerro Punta it "favors borders of streams, edges of clear- 

 ings, and cut-over open woods, rather than heavy forest." In 1961 he 

 found many singing in early April. My own observations were all in 

 February and March of 1954 and 1955, when the notes I took made 

 no mention of singing activity; I did remark, however, that a male 

 collected March 22, 1954, was not breeding. The nest and eggs of the 

 tropical forms of species have not been described. 



So far as known, the Warbling Vireo is insectivorous. Sometimes 

 while foraging they hang upside down while among the terminal twigs. 

 They participate regularly in interspecific foraging flocks. In addition 

 to my own and Eisenmann's observations of this species in mixed 

 flocks, Buskirk et al. (Auk, 1972, p. 619) found that at Cerro Punta 

 Warbling Vireos were part of 25 percent of all flocks observed, al- 

 though they never followed the wandering birds for any distance. 

 Leek (Bird-Banding, 1975, p. 202), who weighed 8 birds that were 

 caught in mist nets at Cerro Punta during September and October of 

 1967 and another 8 the following March and April, found their average 

 weight in "fall," i.e., after the breeding season (12.8 g), higher than in 

 "spring" during the breeding season ( 1 1 .7 g) . 



VIREO GILVUS DISSORS Zimmer 



Vireo gilvus dissors Zimmer, 1941, Amer. Mus. Novit, no. 1127, p. 18. (Cerro 

 Munchique, 7000 ft, west of Popayan, Colombia.) 



Characters. — Crown grayer, not warm brown of chiriquensis; upper 

 surface greener, less brown; undersurface paler, less yellow. 



Measurements. — Males (10 from Colombia), wing 64.2-69.0 (65.9), 

 tail 46.5-51.5 (48.6), culmen from base 10.9-13.9 (12.5), tarsus 16.2- 

 17.3 (16.8) mm. 



Females (10 from Darien and Colombia), wing 62.0-67.9 (65.5), 

 tail 45.6-51.3 (47.7), culmen from base 11.8-12.9 (12.3), tarsus 15.2- 

 17.3 (16.4) mm. 



Resident. Known in Panama from a single specimen, a female col- 



