Swift manuscript dataset

The common swift, Apus apus, is an obligate aerial, migratory, insectivorous bird, that has experienced significant declines in the UK since the 1990s. Reductions in the availability of prey during their summer breeding season in the UK are likely to be a key factor in this decline. This short communication aims to contribute new insights into the current foraging behaviours of adult swifts feeding their nestlings, as a means of provoking new conversation and stimulating further work. Food bolus samples are small ball-like structures containing the insect prey that is regurgitated to nestlings. Boluses from adult swifts provisioning their nestlings were collected incidentally at a breeding colony in Suffolk, UK. These were taxonomically identified and compared to corresponding daily insect catches from a nearby Rothamsted Insect Survey suction-trap operating within the foraging area of common swifts. There was a distinction between contents of the bolus samples and the suction-trap samples, whereby larger bodied aerial invertebrates appeared in greater numbers in bolus samples. This was evidenced by the relatively high numbers of agriculturally important species, pollen beetles and cabbage stem flea beetles, in bolus samples compared to low numbers in suction-traps. Smaller invertebrates such as aphids (Aphididae), parasitoid wasps (Hymenoptera), and thrips (Thysanoptera) were not frequent in the bolus samples, relative to the high numbers identified from the suction-trap catch. These results are discussed in relation to swifts providing a pest suppression service, potential impacts of pesticides, and how selective foraging may both buffer and facilitate the challenges swifts face in a modern agricultural landscape.

普通雨燕（common swift, Apus apus）是一类专性空中生存的迁徙食虫鸟类，自20世纪90年代以来，英国境内的该物种种群已出现显著衰退。夏季繁殖季期间猎物可获得性的下降，大概率是此次种群衰退的关键驱动因素之一。本短篇通讯（short communication）旨在为成年雨燕育雏期的现有觅食行为提供全新研究视角，以期引发学术探讨并推动后续相关研究。食团样本（food bolus samples）指成年雨燕反刍给雏鸟的、包裹昆虫猎物的小球状结构。研究人员在英国萨福克郡的一处雨燕繁殖群落中偶然收集了育雏成年个体吐出的食团样本，对其完成分类学鉴定后，与设置在普通雨燕觅食区域内的邻近罗斯阿姆斯特德昆虫调查（Rothamsted Insect Survey）吸捕诱虫器的每日昆虫捕获量开展对比分析。结果显示，食团样本与吸捕器样本的组分存在显著差异：体型较大的空中无脊椎动物在食团样本中的占比更高。具体表现为，食团样本中农业害虫物种的占比相对较高，如花粉甲虫（pollen beetles）与甘蓝茎跳甲（cabbage stem flea beetles），而这类物种在吸捕器捕获样本中的数量极少。与之相对，吸捕器捕获样本中大量存在的小型无脊椎动物，如蚜虫（Aphididae）、寄生蜂（parasitoid wasps, Hymenoptera）以及蓟马（thrips, Thysanoptera），在食团样本中却并不常见。本文最后围绕雨燕所提供的害虫防控服务、农药的潜在影响，以及选择性觅食如何在现代农业景观中，既能缓解又会加剧雨燕面临的生存挑战等议题展开了讨论。