Origin of the Highland Avifauna of Southern Venezuela

On the origin of the highland avifauna of southern Venezuela. Syst. Zool. 23:257–264.—The highland avifauna of thirteen mountain tepuis of southern Venezuela has been examined through multiple regression analyses to determine which parameters of environmental diversity (area, elevation above sea level) and isolation correlate most strongly with the number of species. A linear model with elevation as the independent variable accounts for 81% of the variation in species number. All independent variables account for 84% of the variation in the multiple regression. This result is discussed in terms of extinction since the last glacial lowering of vegetation zones and it is suggested that elevation and topography may significantly affect the probability of extinction and recolonization. In a comparison of the Pantepui species with two other highland avifaunas, it is shown that the major portion of the variation from the regression of species number on elevation (Fig. 3) is due to the presence of more suboscines than expected, suggesting differential survival during interglacials at higher elevations.