Convergent mechanisms, divergent strategies: a comparison of nectar intake between a generalist and a specialist bat species

Nectar-feeding bats exhibit a range of specialized adaptations that allow them to extract nectar from flowers efficiently. These adaptations include tongue morphological traits and feeding strategies that reflect varying degrees of specialization to nectarivory. While some aspects of the drinking mechanics of highly specialized nectar bats have been studied, little is known about the feeding behaviors of non-specialized species such as Phyllostomus discolor. This study compares the nectar extraction behaviors of P. discolor and the specialized Anoura geoffroyi, examining morphological and biomechanical adaptations that affect feeding efficiency and foraging strategies. We used electron microscopy to study the lingual surface, and high-speed videography to analyze tongue kinematics and feeding efficiency. Both bat species possess hair-like papillae that form a brush-like tongue surface, and both extract nectar using a lapping mechanism; however, they exhibited notable behavioral and biomechanical differences resulting in variation in feeding efficiency. Phyllostomus discolor has a shorter, less flexible tongue than A. geoffroyi, but exhibits similar licking frequencies. Unlike A. geoffroyi, which performs brief hover-feeding bouts, P. discolor perches on the inflorescences, drinks for longer, and extracts more nectar per visit. However, P. discolor exhibited lower feeding efficiency, likely due to its reduced tongue protrusion distance and shorter, less abundant papillae. These findings reveal convergence in general feeding mechanism, i.e. brush-tongue lapping, but highlight divergence in morphological and behavioral traits that affect feeding kinematics and efficiency. Our study illuminates how foraging strategy and tongue morphology affect drinking efficiency, pointing to evolutionary pathways that promote niche differentiation within nectar-feeding bat communities.