FAMILY VIREONIDAE 



213 



As mentioned above, the only information on this species' nesting 

 comes from Skutch's observations in Costa Rica. The 2 nests he found 

 were of typical vireo construction, a cup hung between two slender hori- 

 zontal twigs, built of lichen, moss, bark, and leaf fragments, and silk 

 from insect cocoons and spider webs. The first nest was begun on May 

 21 (in Panama specimens collected by Monniche had enlarged gonads 

 May 1-19 [Blake, op. cit.] ) and the first egg was laid May 29. A second 

 egg, which completed the clutch, was laid the next day. They were 

 ''white, with small, scattered dark spots on the broader end." Both 

 parents incubated, but the nest was destroyed before the eggs hatched. 

 The other nest Skutch found contained young in late June; they were 

 brooded frequently by both parents and were fed larvae. 



VIREO FLAVIFRONS Vieillot: Yellow-throated Vireo, 

 Vireo Gargantiamarillo 



Vireo flavifrons Vieillot, 1808, Hist. Xat. Ois. Amer. Sept., 1(1807), p. 85, pi. 54. 

 (United States [ = eastern United States].) 



Rather small; throat and breast bright yellow, rest of undersurface 

 white; upper surface olive; yellow eye-ring; wings blackish with 

 prominent white wing bars. 



Description. — Length 117-131 mm. Adult (sexes alike) , supra-loral 

 stripe, eye-ring, throat, and breast bright lemon yellow; side of head, 

 and most of upper surface yellowish olive: wings blackish, with middle 

 and greater coverts tipped white, forming two bars, undersurface below 

 breast white. 



Measurements. — Males (10 from Panama), wing 70.3-78.5 (75.2), 

 tail 44.2-50.4 (48.0), culmen from base 11.7-12.5 (12.2), tarsus 17.6- 

 19.2 (18.6) mm. 



Females (10 from Panama), wing 72.0-77.2 (74.8), tail 46.0-50.1 

 (48.3), culmen from base 11.1-13.2 (12.7, average of 9), tarsus 16.1- 

 18.8 (17.6) mm. 



V 'inter visitor from temperate North America, known to winter 

 south to Colombia. Widespread and fairly common, in every province 

 of the Republic. I have also found them on several islands off the 

 Pacific Coast, including San Jose in the Pearl Islands, Taboga, Parida, 

 and Cebaco; I first thought these vireos were simply passage migrants 

 on the islands, but on January 18, 1965, I found 1 in a berry tree on Isla 

 Cebaco, which suggests by the date and source of food that they may 

 winter there. As evidenced from the collecting localities, the Yellow- 

 throated Vireo is found primarily in the lowlands, but in Chiriqui I 

 have also collected it near El Volcan on the Silla de Cerro Pando at 



