Data from: Foraging strategies of generalist and specialist Old World nectar bats in response to temporally variable floral resources

Foraging theory predicts that generalist foragers should switch resources more readily, while specialist foragers should remain constant to preferred food resources. Plant-pollinator interactions provide a convenient system to test such predictions because floral resources are often temporally patchy, thus requiring long-lived pollinators to switch resources seasonally. Furthermore, flowering phenologies range from ‘steady-state’ (low-rewarding but highly reliable) to ‘big-bang’ (high-rewarding but ephemeral) plant species. We assessed how nectarivorous Old World bats respond to this temporally variable floral environment by examining their diets throughout the year. Over 15 months of fieldwork in southern Thailand, we simultaneously: (1) recorded the flowering phenologies of six bat-pollinated plant taxa; and (2) assessed the diets of seven common flower-visiting bat species. As predicted, the generalist nectarivore (Eonycteris spelaea) frequently switched diets and utilized both big-bang and steady-state resources, while the specialist nectarivores (Macroglossus minimus and M. sobrinus) foraged on one or two steady-state plant species year-round. Our results suggest that larger and faster bat species are able to fly longer distances in search of big-bang resources, while smaller bat species rely on highly predictable food resources. This study supports the theory that generalist foragers have flexible diets, while specialist species restrict foraging to preferred floral resources even when other floral resources are more abundant. Moreover, these findings demonstrate how plant flowering phenology and pollinator diet breadth can shape the frequency and constancy of pollinator visits; we further discuss how such interactions can influence the potential extent of gene flow within a patchy floral environment.

觅食理论（Foraging theory）预测，广食性觅食者应更频繁地转换资源，而专食性觅食者应始终取食偏好的食物资源。植物-传粉者互作系统（Plant-pollinator interactions）是验证此类预测的便捷模型，因为花类资源（floral resources）往往在时间上呈斑块状分布，故而长寿传粉者需要在季节间转换觅食资源。此外，植物开花物候（flowering phenologies）涵盖从“稳态型（steady-state）”（低花蜜报酬但高度可靠）到“脉冲爆发型（big-bang）”（高花蜜报酬但花期短暂）的各类植物物种。本研究通过全年监测食性，探究了旧大陆食蜜蝙蝠（nectarivorous Old World bats）对这种时间异质性花类环境的响应模式。研究团队在泰国南部开展了为期15个月的野外调查，同步完成两项工作：（1）记录6种蝙蝠传粉植物类群的开花物候；（2）评估7种常见访花蝙蝠的食性。正如理论预测的那样，广食性食蜜蝙蝠——大长舌果蝠（Eonycteris spelaea）——频繁转换食性，同时利用脉冲爆发型与稳态型花类资源；而专食性食蜜蝙蝠——小长舌果蝠（Macroglossus minimus）与索氏长舌果蝠（M. sobrinus）——全年仅取食1至2种稳态型植物。本研究结果显示，体型更大、飞行速度更快的蝙蝠物种能够飞行更远距离以搜寻脉冲爆发型花类资源，而体型较小的蝙蝠则依赖可预测性极强的食物资源。本研究验证了广食性觅食者食性灵活、专食性物种即便在其他花类资源更为丰富的情况下，仍会局限于偏好的花类资源觅食的理论。此外，本研究结果阐明了植物开花物候与传粉者食性宽度如何影响传粉者访花的频率与持续性；我们还进一步讨论了这类互作如何在斑块状分布的花类环境中影响基因流的潜在范围。