FAMILY TROCHILIDAE 365 



67.2 (65.4), tail 56.0-67.2 (60.2), culmen from base 19.4-22.0 

 (20.8) mm. 



Weight, 1 female, 5.7 grams. (Hartman, Auk, 1954, p. 468.) 



Resident. Fairly common in the Tropical and Subtropical Zones 

 throughout the Republic; to 1,650 meters elevation on Volcan de 

 Chiriqui, above Boquete. 



This is a forest species that in the main frequents the high tree 

 crown, though it comes regularly down into the undergrowth to 

 feed at flowers. The pure white under surface, and the white outer 

 feathers in the long tail are marks that catch the eye as the birds 

 move about, particularly when the tail is expanded as they turn 

 in active flight. At times the long, slender form appears almost 

 insectlike as they move swiftly high overhead. They decoy readily 

 to squeaking sounds, but though they may be called down from high 

 perches move so actively that it is difficult to follow them. On one 

 occasion in a Darien forest one of this species was much disturbed 

 by the squealing of a large woodpecker that we were releasing from 

 a mist net so that it came repeatedly to hover about my head. 



Skutch (Aud. Mag., 1961, pp. 8-9, 13) reports a nest in Costa 

 Rica located "30 feet above the ground in a small tree standing at 

 the edge of a newly made clearing in the rain- forest. . . . The nest 

 was saddled in the elbow of a nearly horizontal twig with a slight 

 upward bend, in the lowest tier of branches far out from the center 

 of the tree. In shape, the structure was a hollow sphere with the 

 upper third more or less cut away to expose the central cavity. As 

 far as I could see ... it was composed of downy materials with 

 none of the lichens or green mosses so frequent in hummingbird 

 nests." 



It is interesting that in this species females may outnumber males in 

 museum collections, instead of the reverse, true in the majority of the 

 species in the family. It is unusual also that the tail in males is 

 decidedly shorter than in females. 



Heliothryx barroti has an extensive range from Tabasco and 

 British Honduras south through Central America, Panama, and 

 western and northwestern Colombia to the middle Magdalena Valley. 

 Within this area the birds appear to be uniform in color and size. 

 The related Heliothryx aurita is found from the Tropical Zone of 

 eastern Colombia, east of the Andes, and from Venezuela south of 

 the Orinoco (with 2 records farther north in Sucre) south to central 

 Bolivia and southern Brazil. In this species the adult male has the 

 crown cap green like the back. Zimmer (Amer. Mus. Nov., no. 1604, 



