Dietary resource overlap among three species of frugivorous bat in Costa Rica

Abstract

AbstractThe maintenance of biodiversity in tropical forests is thought to be dependent on fine-scale mechanisms of niche partitioning that allow species to coexist. This study examined whether three species of short-tailed fruit bat that co-occur at a lowland tropical forest site in Costa Rica (Carollia castanea,C. perspicillata,C. sowelli) avoid inter- and intraspecific competition through dietary specialization on species in the genusPiper. First, dietary composition was examined using faecal samples (N = 210), which yielded three main findings: (1) bat species and sexes vary in overall reliance on fruits ofPiper, with a higher percentage of seeds ofPiperdetected in the diets ofC. castanea(98.2%) and females (91.5%); (2) adults and juveniles partition species ofPiperby habitat, with a lower percentage of mid- to late-successional species ofPiperdetected in adults (20.8%); and (3) overall, there is a strong dietary overlap among and within the three species ofCarollia. Second, controlled choice experiments were conducted with individual bats (N = 123) to examine preferences for different species ofPiper. These results indicated few differences inPiperpreference based on bat species, sex, age class or reproductive status, suggesting preference is not the primary mechanism shaping the observed differences in dietary composition. Overall, the dietary composition and preference similarities suggest there is strong competition both among and within the three species ofCarolliafor food resources.