Nectar drinking efficiency in lonchophylline and glossophagine bats: are “pump-like” or “mop-like” tongues better?

Abstract Nectarivory has independently evolved twice in the bat family Phyllostomidae, resulting in elongated tongues with 2 contrasting morphologies. Glossophagines have lapping “mop-like” tongues with terminal papillae, while lonchophyllines have non-lapping “pump-like” tongues that pull nectar through lateral grooves. Using flight-cage experiments, we measured maximum tongue extension and compared the nectar extraction efficiency of glossophagines and lonchophyllines in flowers with different morphologies and nectar depths. We studied 3 co-existing species in a cloud forest in the Ecuadorian Andes: 2 glossophagines (Anoura caudifer and A. cultrata), and 1 lonchophylline (Lonchophylla robusta). We found that maximum tongue extension is associated with nectar extraction efficiency across the 3 species in that L. robusta, with an intermediate tongue extension, was also intermediate in extraction efficiency. Additionally, within the 2 species of Anoura, individuals with greater tongue extension had greater extraction efficiency. We also found that, across all species, extraction efficiency declined at a similar rate with increasing nectar depths. However, the mechanism behind this decline was different for the glossophagines—which increased visit duration the deeper the nectar—versus L. robusta, which instead decreased visit duration with deeper nectar but simultaneously showed a much sharper decrease in amount of nectar consumed per visit. Our results suggest that bats with “pump-like” and “mop-like” tongues have comparable nectar extraction abilities across a variety of floral shapes, despite the large differences in behavior and tongue morphology. Instead, tongue extension appears to be a better predictor of nectar extraction efficiency, although data from more species are needed to be able to generalize these results.