Niche Differentiation and its Relationship with Food Abundance and Vegetation Complexity in Four Frugivorous Bat Species in Southern Mexico

Species can co-exist within a community when their use of limiting resources is differentiated. To test whether differentiation facilitates coexistence, we quantified differences and overlap in habitat use, fruit consumption, morphological characteristics, and the relationship with vegetation structure for two pairs of ecologically similar frugivorous bat species, Carollia sowelli and C.perspicillata, and Artibeus jamaicensis and A.lituratus. In Carollia sowelli and C.perspicillata, differences in body mass and wing aspect ratio were not reflected in differences in fruit or habitat use (diet overlap, 96 percent; habitat overlap, 98 percent). However, the capture rate of Carollia sowelli positively correlated with canopy openness, and that of C.perspicillata positively correlated with tree height. Body mass and wing characteristics of Artibeus species suggested a greater maneuverability for A.jamaicensis. Also, more A.jamaicensis individuals were captured feeding on Ficus spp., while Artibeus lituratus preferred fruits of the early successional tree Cecropia. However, both habitat overlap and diet overlap were higher than by chance (diet overlap, 75 percent; habitat overlap, 92 percent). The co-existence of the four bat species in the study area may be facilitated by the abundance of the food resources forming part of the diets of both Carollia species, by the morphological differences between the Artibeus species, which allow the differentiation of foraging behavior in relation to fruit consumption, and by the structural characteristics of the vegetation. Resumen La coexistencia de especies en una comunidad es posible cuando el uso de recursos limitados se diferencia. Para probar si la diferenciacion facilita la coexistencia, cuantificamos desigualdades y traslapes en el uso de habitat, consumo de frutos, caracteristicas morfologicas, y la relacion con la estructura vegetal en dos pares de especies de murcielagos frugivoros ecologicamente similares: Carollia sowelli y C. perspicillata, y Artibeus jamaicensis y A. lituratus. En C. sowelli y C. perspicillata, las diferencias en masa corporal y la relacion del aspecto alar no se reflejaron en diferencias en el consumo de frutos o uso del habitat (traslape de dieta 96%; traslape de habitat 98%). Sin embargo, la cantidad de capturas de C. sowelli se correlaciono positivamente con la apertura de dosel, y la de C. perspicillata con la altura de los arboles. La masa corporal y caracteristicas morfologicas de las alas de los Artibeus sugieren una mayor maniobrabilidad en A. jamaicensis, igualmente mas individuos de A. jamaicensis fueron capturados alimentandose de Ficus spp., mientras que A. lituratus prefirio frutos de Cecropia, un arbol de etapa sucesional temprana. Sin embargo, el traslape de habitat y la dieta fueron mayores a lo esperado por probabilidad (traslape de dieta 75%; traslape de habitat 92%). La coexistencia de las especies de murcielagos estudiados en el area puede verse facilitada debido a la abundancia de recursos alimenticios que forman parte de la dieta de las dos especies de Carollia, y por las diferencias morfologicas entre las dos especies de Artibeus que permiten la diferenciacion del comportamiento de forrajeo en relacion con el consumo de frutos y las caracteristicas estructurales de la vegetacion.