Good to the Last Drop: Feeding Behavior of the Nectar Bat Leptonycteris yerbabuenae (Chiroptera, Phyllostomidae) at Hummingbird Feeders in Tucson, Arizona

Many individuals of the nectar-feeding phyllostomid bat, Leptonycteris yerbabuenae, visit hummingbird feeders in southern Arizona for nearly three months each year prior to migrating back to Mexico. We monitored bat activity at four feeders with trail cameras or security cameras all night for 19–57 nights during the 2021 ‘nectar bat season’. As in previous years, peak visits occurred in mid-September. Detailed analysis of data from one feeder on 22 nights indicated that non-adults (juveniles and yearlings) were visiting it and that visitation patterns were highly variable from night to night. Statistical analysis of these patterns revealed that clusters of bats were visiting this feeder more often than expected by chance, suggesting that bats are foraging in groups. Surprisingly, bats did not leave feeders once they were drained but continued to visit them for up to five hours each night. Energetic calculations suggest that some bats are potentially expending half of their foraging energy visiting empty feeders. Studies of individually tagged bats are needed to begin to understand this behavior.