Assessing the Role of Interspecific Competition in Shaping the Diurnal Activity Patterns of Saccopteryx leptura in an Insular Environment

Understanding the daily activity patterns of species is essential for unravelling the complex strategies animals use for survival and reproduction. These patterns dictate when and how animals interact with their environment, but some species exhibit surprising deviations from their usual activity patterns. In the Gorgona National Natural Park, the lesser sac-winged bat Saccopteryx leptura displays extended diurnal activity that varies spatially depending on the island's vegetation cover. To understand this behaviour, we evaluated whether the extent of diurnal activity is a strategy to avoid nocturnal competition with other insectivorous bats. To this end, we used ultrasonic recorders to capture echolocation pulses at sites with different vegetation covers. We aimed to analyse how the activity patterns of S. leptura and other common insectivorous bats on the island vary spatially. Overall, we found that S. leptura exhibits a diurnal activity peak that extends after sunrise and two nocturnal peaks, contrasting with its insular populations and other species that peak at dawn and night. Furthermore, the diurnal activity pattern varies spatially with vegetation cover, and they are more active at sites with a high night-time activity of other common insectivorous bats on the island, with which they overlap in foraging sites and echolocation frequencies such as Eptesicus chiriquinus and Myotis nigricans. The results suggest that S. leptura adjusts its behaviour to reduce resource competition or acoustic interference, offering a novel perspective on animals' adaptability in insular environments.