NESTING HABITS OP OBOPENDOLA — CHAPMAN 381 



I can present only ti theoretical interpretation of the actions of 

 this pair of birds. To me they indicate that the contents of their 

 nest (Xo. 2, Group 2) havini; been destroyed by nii^'ht attack, the 

 female deserted. The male then attracted the attention of another 

 female but did not succeed in winning her as a mate. 



ASSOCIATED SPECIES 



The sand-box tree in which the oropendolas nest forms an attrac- 

 tive and advantageous perch, particularly for birds that cross the 

 clearing. During the period covered by these observations I have 

 seen slightly over 50 species of birds in it. Four of these species, in 

 addition to Zarhyncliu^ and Leyatus, nest in the tree; they are the 

 violet-throated humming bird {Anthracothorax violaceicollis) ^ the 

 Colombian flycatcher {Myiuzetetes tcxensis columhlanus), Natterer's 

 cotinga {Cotlnya natteren) ^ and the blue tanager {Thraupis cana). 

 Of all the birds seen in the tree, only six appear to have direct asso- 

 ciation with Zarhynchus. They are a cowbird {Cassidix oryzivo/a), 

 a fl3'catcher {Leyatus alhicoUis), a hawk {Splzafttur melanoleucus) ^ 

 an owl [Puhati'ix perspiclllafa), a cacique {Caclcus vitellinus) and 

 a humming bird {Anthracothorax nlgncoUls). 



The first two are parasitic, the second two, predaceous. Their 

 observed relations to Zarhynchus have already been described under 

 the section devoted to the enemies of Zarhyyichus. The relations of 

 the remaining two I will speak of here. 



Cacicus viteUinua. — From the beginning to the end of the nesting 

 season, as I have observed it, usually one caci(|ue is present in the 

 nest tree acting as though it were a member of the colony. Rarely 

 two males were seen, and on February IG two males and two females 

 were in the tree at the same time. One male, however, is the normal 

 Cacicus representative. This bird often arrives as soon as the first 

 Zarhynchus^ and it, or another, may be in the tree the greater part 

 of the day. It makes no attempt to associate closely with Zarhynchus 

 and does not perch very near the nests, its chief activity being the 

 delivery of its calls. While bearing a general resemblance to those 

 of Zarhynchus the notes of Cacicus are more varied, more musical 

 and louder, and they are uttered more continuously and more insist- 

 ently, at times for an hour or more without ceasing. In view of the 

 fact that no other individual of its own species is in the tree or ap- 

 parently near, and that the bird addresses only a general and un- 

 responsive audience, its energy and ])ersistencc are inexplicable. 

 At its maxhnum the delivery of its notes is accompanied by an in- 

 teresting display in which the wing tips are crossed beneath the tail 

 and behind the feet, the yellow rump feathers fluffed and expanded, 

 while the wings and tail are violently treml)led. This continues for 

 several minutes as the bird calls loudly. Occasionally a male 



