33§ 



BIRDS OF THE REPUBLIC OF PANAMA PART 4 



The large Montezuma Oropendola feeds almost entirely on fruit and 

 nectar, for which it travels considerable distances from its colonial 

 nesting sites. Its flight is crowlike and direct. When feeding high in 

 the tree tops this species is rather shy, and some of its food habits may 

 have been overlooked; in Costa Rica, Larry Wolf (Wilson Bull., 1971, 

 pp. 197-198) saw an oropendola catch and kill a fledgling Black- faced 

 Grosbeak (Caryothraustes canadensis) that was part of a flock feeding 

 in a tree. A male collected by Strauch (Bull. Brit. Orn. Club, 1977, p. 

 64) weighed 528.5 g; a female weighed 241.8 g. 



This is a very vocal species. The male sings through most of the year, 

 delivering a series of loud gurgling notes as he bows forward and raises 

 his wings and then brings himself upright again. Once at El Uracillo 

 I saw a male display by calling and opening his wings before his mate, 

 who was on the branch beside him. He then moved over and touched 

 her with his bill, finally pecking her on the rump; this was repeated 

 several times. Both sexes also have several loud clucking and cacking 

 calls. 



The Montezuma Oropendola nests in large and conspicuous colonies 

 in open areas in trees that are inaccessible to most predators. I have 

 found active colonies during February and March in Bocas del Toro 

 and western Colon. One colony on the Changuinola Canal in Almirante 

 had approximately 25 nests on February 20, 1958. Females always 

 considerably outnumber males. The Canal Zone area colonies are 

 active from January to at least May, or sometimes early June; by July, 

 nesting trees are deserted, and birds wander about in noisy bands. 



Skutch (Pac. Coast Avif., no. 31, 1954, pp. 287-304) has observed 

 the nesting of this species in Costa Rica, where the season begins in 

 January. One colony in a group of trees included 61 nests. The nests 

 are placed on the outer twigs of trees from 13 to at least 33 m off the 

 ground; they are hanging pouches 60 to 120 cm long and 18 to 23 cm in 

 diameter near the bottom. It takes the female approximately 10 days, 

 working alone, to weave the nest basket, which is made of long fibers 

 of banana leaves, vines, and palm leaves, and she spends another 3 to 6 

 days adding dead or dying leaves to the lining. Much of the nest ma- 

 terial is brought from far away, but oropendolas also steal whatever 

 they can from unattended nests. When not actually courting, the sexes 

 ignore one another in the nest tree; the males provide no assistance in 

 building or later in incubation or feeding the young, but they serve as 

 sentries and accompany females gathering nest material. 



An egg in the British Museum collected in Costa Rica by C. F. Un- 

 derwood was long and oval, dull buffy white with numerous scattered 



