354 BIRDS OF THE REPUBLIC OF PANAMA PART 4 



Monniche (Blake, Fieldiana: Zool., vol. 36, no. 5, 1958, pp. 563-564) 

 collected it on the Volcan de Chiriqui between 1590 and 2910 m and 

 W. W. Brown, Jr., found it there between 2850 and 3090 m (Bangs, 

 Proc. New England Zool. Club, vol. 3, 1902, p. 64). In Code it has 

 been collected at 750 m at El Valle, and in Darien at 600 m at Cana. I 

 have not found it in the lowland scrub of the drier eastern side of the 

 Azuero Peninsula, though it occurs in the more humid western slope 

 in this area, where Aldrich and Bole (Scient. Publ. Cleveland Mus. 

 Nat. Hist., vol. 7, 1927, pp. 24-25) considered it common in semi- 

 deciduous coastal forest near Monti jo Bay, Veraguas, and uncommon 

 in rain forest between 300 and 900 m. This race also occurs north to 

 central Mexico and south to northern Colombia; other races are found 

 south to eastern Peru and Bolivia. 



The race centralis of Costa Rica and Panama, described by Todd 

 (Proc. Biol. Soc. Wash., 1916, 29, p. 95) as having the wings longer 

 than the tail, rather than the reverse, as supposedly found in popula- 

 tions farther north, is not valid. Both Peters (Bull. Mus. Comp. Zool., 

 71, no. 5, 1931, p. 475) and Hellmayr (Cat. Birds Am., vol. 13, pt. 10, 

 1937, p. 43) concluded that differences are due to individual variation. 

 In a large series of specimens from Panama, as many have the tail 

 longer than the wings as the reverse. 



The Yellow-billed Cacique inhabits dense thickets in forest openings 

 and edge, second growth, abandoned fields, and, occasionally even man- 

 groves, mostly at their edge or near islands of higher ground where 

 there is some low vegetation. It is far more often noted by its calls than 

 its appearance. In handling these birds I noticed that they lack the 

 pungent odor of the other caciques and oropendolas. The male has a 

 variety of pleasant whistling notes as well as the harsh, often explo- 

 sive, calls that are given by both sexes; one that I noted was a wrenlike 

 chatter, chruh-chruh-chruh. When seen, the birds often seem quite jay- 

 like in movement, often resting with the tail hanging straight down. 

 Rarely does one stay long in the open. So far as has been reported, 

 they feed exclusively on insects. Ridgely (in litt.) has at least once 

 seen a pair attending a small army-ant swarm. He has also seen them 

 in flowering and fruiting trees, but it was not clear that they were feed- 

 ing on anything but insects. One that I was able to watch closely at 

 Chiva Chiva, Canal Zone, was climbing slowly about in heavy under- 

 growth, keeping under cover. Several times I saw it pull masses of 

 lodged dead leaves apart. Later it came out higher up on a slender 

 dead branch that had some insect infestation. Repeatedly it thrust the 



