4IO BIRDS OF THE REPUBLIC OF PANAMA PART 4 



outer two pairs almost entirely white; entire undersurface rich yellow; 

 underwing coverts white. 



Adult female, sides of head and entire upper surface, including wing 

 coverts, olive-green, slightly more yellowish on forecrown and upper 

 tail coverts; remiges and rectrices dusky blackish, with outer webs 

 edged greenish yellow; undersurface greenish yellow, except for white 

 belly; underwing coverts white. 



Measurements. — Males (10 from Costa Rica), wing 60.5-65.2 

 (62.5), tail 31.6-36.7 (34.1) culmen from base 9.2-10.6 (9.9), tarsus 

 13.6-15.0 (14.6) mm. 



Females (10 from Costa Rica and Nicaragua), wing 58.0-63.0 

 (60.7), tail 29.3-34.2 (31.4), culmen from base 8.2-9.8 (9.3), tarsus 

 13.9-15.3 (14.6, average of 9) mm. 



Resident. Rare and local in western Chiriqui, where W. W. Brown, 

 Jr., collected 2 adult males at Boquete between 1140 and 1200 m 

 (Bangs, Proc. New England Zool. Club, vol. 3, 1902, p. 64). These 

 may perhaps have been re-identified as E. laniirostris, as R. A. Payn- 

 ter, Jr. {in litt. to Olson) writes that there are no Panamanian speci- 

 mens of E. hirundinacea in the MCZ collections. Because this species 

 is so similar to E. laniirostris, specimen evidence of its occurrence in 

 Panama is still needed. Ridgely (in litt.) has seen 1 or 2 individuals 

 of this species occasionally around El Volcan, most recently a female at 

 the Dos Rios Hotel grounds on February 3, 1976. This race is com- 

 moner in Costa Rica and northwestern Nicaragua; the nominate form 

 ranges north to eastern Mexico. 



Skutch (Pac. Coast Avif., no. 31, 1954, pp. 247-251) has observed 

 this euphonia in Guatemala and Costa Rica, where it inhabits the tops 

 of trees in woodland edges and partly cleared areas. It feeds exten- 

 sively on mistletoe berries. The only song Skutch has heard is a short 

 two- or three-note whistle; the female has a call similar to the male's 

 but thinner and more trilled. In Guatemala the nesting season is from 

 March until at least late May. The nest is placed from 1 to more than 

 2.5 m from the ground in a cranny or sheltered nook; it is a globular 

 structure made of fine tendrils and other vegetation all bound with cob- 

 webs and lined with small, dry grass blades. Both sexes assist in con- 

 struction. Five eggs seem to form the usual clutch. They are white, 

 heavily blotched with umber, especially on the blunter end; six eggs 

 averaged 16.3 X 12.8 mm. The incubation period is 16 days. The young 

 develop slowly; when 8 days old they still have few feathers, although 

 by 15 days they are well feathered. In one nest the young left at 17 

 days of age. 



