Bat functional diversity in two livestock production farms in Guanacaste, Costa Rica

Abstract

Introduction: Livestock activities are one of the main causes of the loss and degradation of tropical forests. Consequently, groups of organisms such as bats are affected, impacting the ecosystem services they provide. The analysis of the functional structure of bat assemblages allows to effectively know the characteristics and responses of the species in an ecosystem, thus contributing to the assessment of conservation status of the environments. Objectives: To describe the functional structure of fruit bat assemblages in two livestock farms in Guanacaste, Costa Rica. Methods: Two functional traits related to body size (body mass and forearm length) were measured in fruit bats captured with mist nets in two localities (Nambí and Hojancha). From these traits, the functional diversity of the assemblages was quantified by using the functional richness index, evenness, and functional dispersion, and the weighted mean of these assemblages was calculated. To identify the functional groups of bats, a hierarchical clustering method based on principal component analysis was used, followed by the calculation of Euclidean distances. Results: A total of 191 individuals (14 bat species and two families) were captured. Of the species captured, nine correspond to fruit-eating bats of the subfamilies Stenodermatinae and Carollinae. The bat assemblage of Nambí presented greater functional richness than Hojancha, while the indexes of evenness and functional dispersion were similar in both sites. Conclusion: A higher functional richness of the bat assemblage at Nambí with respect to Hojancha indicates a greater amount of resources exploited by fruit-eating bats. Consequently, bats in this community could be providing greater environmental services compared to Hojancha, which evidences the importance of their conservation for the maintenance of ecological communities in anthropic ecosystems.