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BIRDS OF THE REPUBLIC OF PANAMA PART 4 



figs. E. A. Goldman recorded the stomach contents of 2 that he col- 

 lected: one contained 11 caterpillars, 9 of one species, 2 of another 55%, 

 25 seeds with bits of red fruit pulp surrounding them 45%; the other 

 had bits of 2 ants 10%, a large otiorhynchid near Lachnopus 10%, re- 

 mains of two other weevils 5%, elytron of another beetle trace, 58 

 seeds undetermined, a few other smaller ones, and a mass of vegetable 

 fiber 75%. A male collected by Strauch (Bull. Brit. Orn. Club, 1977, 

 p. 64) weighed 94.9 g. 



Caciques call constantly with a series of highly varied conversational 

 notes; these are closely similar to those of Psarocolius wagleri, but with 

 fewer bubbling calls and explosive notes, and, in all, more musical. 

 Some that I noted are wick-a-weo, char-che-ar, chock-chu-chou, wicka- 

 wicko, and chut- chu- chut. The female seems limited to liquid chirps 

 and clucks. 



Although they sometimes nest with oropendolas, the cacique's breed- 

 ing season appears to start somewhat later. It may depend on locality 

 and the rainfall or dryness of a particular year. On March 9, 1957, at 

 Pedasi, Los Santos, I watched a male displaying before a female 

 perched beside him; the male arched his neck and raised the feathers 

 there and on the rump and gave his gabbling calls. During April of 

 1949, I found several colonies in the Province of Panama that were 

 still under construction: near Cerro Azul I saw a group starting a new 

 colony in a tree in recently cleared fields at San Miguel on April 19, 

 and at Chepo I watched females carrying nest material to a colony on 

 April 26. Skutch, who studied this species in 1935 at Barro Colorado 

 Island in the Canal Zone (Pac. Coast. Avif. no. 31, 1954, pp. 305-315) 

 found them building nests there during April and early May. 



The nest is a hanging pouch woven from strips of palm fronds and 

 fibrous strands of leaves and vines, and is lined with softer fibers. It 

 is 30 to 45 cm long, generally shorter and more oblong than oropendola 

 nests. Eisenmann points out that the nests are placed closer together, 

 often touching each other. In South America caciques have evolved an 

 interesting adaptation that makes nesting in the rainy season less dif- 

 ficult: when the rains begin in the middle of the breeding cycle the fe- 

 male weaves a roof over the nest entrance so that the interior remains 

 dry (Cherrie, Mus. Brooklyn Inst. Arts and Sci. Bull, 2, 1916, p. 204). 

 This has not been observed in Panama, but it is certain that Yellow- 

 rumped Caciques have not finished raising their young by the beginning 

 of the rainy season. When not in a tree surrounded by a clearing, the 

 colony is sometimes over water, as the 1 Skutch watched and 1 that I 

 found at Chepo that consisted of 15 nests hung from a pendant branch 



