56 Bulletin American Museum of Natural History. [Vol. XXXVI, 



The scarcity of arborescent vegetation at Quetame necessarily limited 

 the numbers of species of birds found there. Altitudinally in the Sub- 

 tropical Zone, only the scanty growth of timber along streams flowing into 

 the Rio Negro itself furnishes a haunt for the tree-inhabiting species of this 

 zone, but in such localities the few species secured were members of the zone 

 in which Quetame is situated. Examples are Xanthoura cyanodorsalis, 

 Grallaria ruficeps, and Cinclus. 



But mingled with these birds were outlying representatives of the Tropic 

 Zone below; for example Planesticus ignobilis and Tanagra- episcopus, whUe 

 on the grassy hillsides or along the hedge-rows such characteristic species 

 \ of the Temperate Zone as Sturnella meridionalis and Planesticus gigas found 

 ■their lower limit. At Quetame, then, although the avifauna was in the main 

 that of the Subtropic Zone, representatives of both the zone below (Tropic) 

 and zone above (Temperate) met, a condition we have not found elsewhere. 



At Monteredondo, some five miles east of Quetame, but at about the 

 same altitude (4800 ft.), arborescent vegetation was somewhat more 

 developed and from this point it increased steadily in size and abundance. 

 Ten miles further east the mountain slopes rising from the southern side of 

 the Rio Negro were heavily forested from base to summit, here a matter 

 of about 3000 feet, but the slopes on the northern .side, or those having a 

 southerly exposure, were still comparatively bare; a condition possibly due 

 to the fact that the prevailing winds are northeast rather than southeast. 



As we traveled-_eastward the iorested areas continued to increase, the 

 most eastern ridge of the range being covered with superbly developed 

 primeval woods from the Llanos at their base to their crest (alt. 4500 ft.). 

 On the western side, where the slopes reached the Rio Negro, now 

 some 2500 feet below, the forest continued to the water's edge. In this 

 region we made our base at the posada of Buena Vista, situated at the side 

 of the trail on the summit of the ridge directly above Villavicencio lying 

 some 3000 feet below at the base of the Andes. 



Buena Vista was our most productive station. From the surrounding 

 region have come many Bogota skins. Within two hundred yards of the 

 posada lie as finely developed tropical forests as I have ever entered; the 

 trees are of exceptional height (averaging over one hundred feet), the forest 

 floor is comparatively open. Numerous trails greatly facilitate the. passage 

 of the collector and I recall with unalloyed pleasure our experiences in this 

 delightful locality. 



The fauna of Buena Vista is mainly that of the Tropical Zone, with the 

 addition of some species from the zone above. The fact, however, that the 

 ridge reaches an altitude of only 4500 feet, and that there are no higher 

 ridges nearby, evidently limits the number of Subtropical Zone representa- 

 tives. 



