Body size variation in Amazonian bats: patterns across species, sexes, and landscapes in the Colombian tropical rainforest

The Amazon rainforest harbors one of the world’s most diverse bat faunas, yet studies examining body size variation using multiple morphological traits and ecological factors remain scarce. We evaluated body size variation across species, sexes, and landscapes in bats from the Colombian Amazon using five years of field data. We characterized 956 adult individuals from 35 species using four traits: forearm length, wingspan, hind foot length, and ear length. Juveniles and pregnant females were excluded to avoid ontogenetic and reproductive biases. ANOVA was used for interspecific comparisons, t-tests for sexual dimorphism and landscape effects, and reduced major axis regression to test Rensch’s rule. We found significant interspecific variation in body size traits associated with phylogenetic, trophic, and ecological differences. Unlike Rensch’s rule, size variation followed an isometric pattern, although some species exhibited female-biased size, partially supporting the ‘Big Mother’ hypothesis. Morphological differences among landscapes were found: only species of Carollia had longer forearms and wingspans in mountainous areas, whereas species of Carollia, Artibeus, Mesophylla, and Rhinophylla had longer ears in hilly regions. Together, these findings highlight the influence of ecological pressures and landscape heterogeneity on body size variation in Amazonian bats, with ear length showing the strongest landscape-related variation.