Ensemble Composition and Activity Levels of Insectivorous Bats in Response to Management Intensification in Coffee Agroforestry Systems

Shade coffee plantations have received attention for their role in biodiversity conservation. Bats are among the most diverse mammalian taxa in these systems; however, previous studies of bats in coffee plantations have focused on the largely herbivorous leaf-nosed bats (Phyllostomidae). In contrast, we have virtually no information on how ensembles of aerial insectivorous bats – nearly half the Neotropical bat species – change in response to habitat modification. To evaluate the effects of agroecosystem management on insectivorous bats, we studied their diversity and activity in southern Chiapas, Mexico, a landscape dominated by coffee agroforestry. We used acoustic monitoring and live captures to characterize the insectivorous bat ensemble in forest fragments and coffee plantations differing in the structural and taxonomic complexity of shade trees. We captured bats of 12 non-phyllostomid species; acoustic monitoring revealed the presence of at least 12 more species of aerial insectivores. Richness of forest bats was the same across all land-use types; in contrast, species richness of open-space bats increased in low shade, intensively managed coffee plantations. Conversely, only forest bats demonstrated significant differences in ensemble structure (as measured by similarity indices) across land-use types. Both overall activity and feeding activity of forest bats declined significantly with increasing management intensity, while the overall activity, but not feeding activity, of open-space bats increased. We conclude that diverse shade coffee plantations in our study area serve as valuable foraging and commuting habitat for aerial insectivorous bats, and several species also commute through or forage in low shade coffee monocultures.遮阴咖啡种植园因其在生物多样性保护中的重要作用而受到广泛关注。蝙蝠是该生态系统中物种多样性最为丰富的哺乳动物类群之一；然而以往针对咖啡种植园蝙蝠的研究，多聚焦于以植食性为主的叶口蝠科（Phyllostomidae）物种。与之形成鲜明对比的是，我们几乎对占新热带区蝙蝠物种近半数的空中食虫蝙蝠群落如何响应生境改造一无所知。 为评估农业生态系统管理方式对食虫蝙蝠的影响，我们在以咖啡农林业为主导景观的墨西哥恰帕斯州南部，开展了蝙蝠多样性与活动模式相关研究。我们通过声学监测与活体捕捉技术，对森林片段以及遮阴树结构和分类学复杂度存在差异的咖啡种植园中的食虫蝙蝠群落进行了特征刻画。本次研究共捕捉到12种非叶口蝠科蝙蝠；声学监测则额外发现了至少12种空中食虫蝙蝠物种。 所有土地利用类型中的林栖蝙蝠物种丰富度均无显著差异；与之相反，在遮阴度低、管理强度高的咖啡种植园中，开阔空间蝙蝠的物种丰富度有所提升。反之，仅林栖蝙蝠的群落结构（以相似性指数衡量）在不同土地利用类型间存在显著差异。随着管理强度升高，林栖蝙蝠的总活动量与觅食活动量均显著下降；而开阔空间蝙蝠的总活动量有所上升，但觅食活动量无明显变化。 本研究结论表明，研究区域内的多样化遮阴咖啡种植园可为空中食虫蝙蝠提供优质的觅食与通勤栖息地，且部分物种也会在低遮阴的单一栽培咖啡园中穿行或觅食。