A comparative study of the forebrain of 4 species of South American birds.

The brains of the swift Streptoprocne zonaris, the flycatcher Tyrannus melancholicus, the tanager Ramphocelus dimidiatus and the finch Oryzoborus angolensis were compared with respect to the hyperstriatum accessorium, hyperstriatum dorsale, hyperstriatum ventrale, neostriatum, ectostriatum, paleostriatum augmentatum and paleostriatum primitivum. In each of these brain parts the average number of cells and the average cell size were calculated, and the species were compared with respect to the same part of the brain. Some of the data suggest that the density and size of cells are correlated with behavior (e.g. feeding behavior), but such correlations should be confirmed with electrophysiological studies as well as cytoarchitectural studies of more species which exhibit similar feeding behavior.