Persistence of frugivorous bats in fragments of high-andean forests: a model of structural equations

Studies of high-altitude frugivorous bats in Colombia have focused on their diet, taxonomy, systematics, and geographic distribution. Aspects related to the proximal mechanisms that determine their ensemble structure and conservation problems have been largely neglected. To evaluate how frugivorous bats are assembled in fragments of high-Andean Forest, the diversity, abundance and replacement rate of groups of high-altitude bats were compared between fragments and continuous areas of high-Andean forest over three years. Simultaneously, the abundance of fruits and nocturnal insects was measured at all sites, as well as the vertical and horizontal structure of the vegetation. The simultaneous effect of the changes in availability of food and the structure of the vegetation on these groups of frugivorous bats was analyzed by developing models based on structural equations. These models indicated that the species richness of frugivorous bats diminished in forest fragments due to a reduction of the available height for foraging, which in turn was correlated with increases in secondary growth plant species and with increase of undergrowth cover and the sub-canopy. Finally, we present dynamic models that explain the mechanisms that control ensembles of frugivorous bats in high-Andean forests, and we discuss implications for high altitude bat conservation. Our study highlights that fragmentation could increase rare bat species vulnerability to extinction on a local level due to the structural variations of vegetation. Given that frugivorous bats are the dominant group in mountain regions, preserving continuous areas of high-Andean forests is essential for effective management and conservation of bat biodiversity.