Changes in Bat Species Diversity along an Elevational Gradient up the Peruvian Andes

Changes in chiropteran species diversity and richness along a generalized transect up the eastern slopes of the Peruvian Andes are described. Variation in overall species diversity, species richness, and evenness are closely correlated with elevation. A decrease in bat density along the gradient is indicated by elevational decrease in sample size and by significant elevational reduction in the number of bats netted per unit effort. Explanations for these patterns are offered based on significant correlations of temperature and foliage height diversity with both overall richness and number of species in major feeding guilds. The conclusion is that diversity changes in the bat community along the gradient are caused by many factors, both historical and contemporary. The slopes of the Andes probably were colonized, for the most part, from the adjacent older lowlands of the Amazon Basin where most of the speciation took place. Immigration into the highlands has been (is) impeded by the reductions in temperature, habitat complexity, and levels of food abundance acting independently or collectively.