Birds provide ecosystem services (pest control) in many agroecosystems and have neutral or negative ecological effects (disservices) in others. Large-scale, conventional row crop agriculture is extremely widespread globally, yet few studies of bird effects take place in these agroecosystems. We studied indirect effects of insectivorous birds on corn and soybean crops in fields adjacent to a prairie in Illinois (USA). We hypothesized that prairie birds would forage for arthropods in adjacent crop fields and that the magnitude of services or disservices would decrease with distance from the prairie. We used bird-excluding cages over crops to examine the net effect of birds on corn and soybean grain yield. We also conducted DNA metabarcoding to identify arthropod prey in fecal samples from captured birds. Our exclosure experiments revealed that birds provided net services in corn and net disservices in soybeans. Distance from prairie was not a significant predictor of exclosure treatment effect in either crop. Many bird fecal samples contained DNA from both beneficial arthropods and known economically significant pests of corn, but few economically significant pests of soybeans. Song Sparrows (Melospiza melodia), one of our most captured species, most commonly consumed corn rootworms, an economically significant pest of corn crops. We estimated that birds in this system provided a service worth approximately US $275 ha⁻¹ in corn yield gain, and a disservice valued at approximately $348 ha⁻¹ in soybean yield loss. Our study is the first to demonstrate that birds can provide substantial and economically valuable services in field corn, and disservices in soybean crops. The contrasting findings in the 2 crop systems suggest a range of bird impacts within widespread agroecosystems and demonstrate the importance of quantifying net trophic effects.

中文翻译：

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在混合草原/农业系统中，鸟类抑制玉米中的害虫，但将它们释放到大豆作物中。


鸟类在许多农业生态系统中提供生态系统服务（害虫防治），但在其他农业生态系统中具有中性或负面的生态影响（损害）。大规模的传统中耕作物农业在全球范围内极为普遍，但对这些农业生态系统中鸟类影响的研究却很少。我们研究了食虫鸟类对美国伊利诺伊州大草原附近的玉米和大豆作物的间接影响。我们假设草原鸟类会在邻近农田中寻找节肢动物，并且服务或损害的程度会随着距草原的距离而减少。我们在农作物上使用了排除鸟类的笼子来检查鸟类对玉米和大豆谷物产量的净影响。我们还进行了 DNA 元条形码编码，以识别捕获的鸟类粪便样本中的节肢动物猎物。我们的排除实验表明，鸟类在玉米中提供净服务，在大豆中提供净损害。与草原的距离并不是这两种作物的排除处理效果的显着预测因素。许多鸟类粪便样本含有来自有益节肢动物和已知具有经济意义的玉米害虫的 DNA，但很少含有具有经济意义的大豆害虫。歌麻雀 ( Melospiza melodia ) 是我们捕获最多的物种之一，也是最常食用的玉米根虫，是一种对玉米作物具有重要经济意义的害虫。我们估计，该系统中的鸟类为玉米产量增加提供了价值约 275 美元 ha ^-1的服务，并为大豆产量损失提供了价值约 348 美元 ha ^{-1 的}损害。我们的研究首次证明鸟类可以为大田玉米提供大量且具有经济价值的服务，并为大豆作物提供损害。 两种作物系统的对比发现表明鸟类对广泛的农业生态系统产生了一系列影响，并证明了量化净营养效应的重要性。