Data from: Concealed by darkness: interactions between predatory bats and nocturnally migrating songbirds illuminated by DNA sequencing

Recently, several species of aerial hawking bats have been found to prey on migrating songbirds, but details on this behavior and its relevance for bird migration are still unclear. We sequenced avian DNA in feather-containing scats of the bird-feeding bat Nyctalus lasiopterus from Spain collected during bird migration seasons. We found very high prey diversity, with 31 bird species from 8 families of Passeriformes, almost all of which were nocturnally flying sub-Saharan migrants. Moreover, species using tree hollows or nest boxes in the study area during migration periods were not present in the bats’ diet, indicating that birds are solely captured on the wing during nighttime passage. Additional to a generalist feeding strategy, we found that bats selected medium sized bird species, thereby assumingly optimizing their energetic cost-benefit balance and injury risk. Surprisingly, bats preyed upon birds half their own body mass. This shows that the 5% prey to predator body mass ratio traditionally assumed for aerial hunting bats does not apply to this hunting strategy or even underestimates these animals’ behavioral and mechanical abilities. Considering the bats’ generalist feeding strategy and their large prey size range, we suggest that nocturnal bat predation may have influenced the evolution of bird migration strategies and behavior.近年来，已有研究发现数种空中掠食性蝙蝠以迁徙鸣禽为食，但有关该捕食行为的细节及其对鸟类迁徙的相关意义仍尚不明确。我们对采集自西班牙、于鸟类迁徙季节收集的食鸟蝙蝠大夜蝠（Nyctalus lasiopterus）的含羽毛粪便中的鸟类DNA进行了测序。结果显示其猎物多样性极高，共检测到雀形目（Passeriformes）8个科下的31种鸟类，且几乎全部为夜间飞行的撒哈拉以南迁徙鸟类。此外，在研究区域内迁徙期间依赖树洞或人工巢箱栖息的鸟类并未出现在该蝙蝠的食谱中，这表明该蝙蝠仅在鸟类夜间飞行过境时将其空中捕获。除了广谱的取食策略外，研究还发现该蝙蝠偏好选择中等体型的鸟类，进而推测此举可优化其能量成本收益平衡与捕猎时的受伤风险。令人意外的是，该蝙蝠竟能捕食相当于自身体重一半的鸟类。这表明，传统认为空中捕猎蝙蝠的捕食者与猎物体重比为5%的结论，并不适用于该类捕食策略，甚至可能低估了这些动物的行为与机械能力。考虑到该蝙蝠的广谱取食策略及其宽泛的猎物体型范围，我们认为夜间蝙蝠捕食行为可能对鸟类迁徙策略与行为的演化产生了影响。