Assessing the influence of raptors on grape-eating birds in a Mediterranean vineyard

Several bird species may cause serious damage to grape production. The ability of raptors as biological control agents of grape-eating birds is poorly understood and under-used. We installed artificial nests and perches to encourage the presence and activity of raptors in vineyards located in central Spain and explored their effectiveness to reduce damage to grapes. We characterized the raptor community by field surveys and assessment of natural breeding sites, evaluated the abundance of grape-eating birds, and sampled damage to grape production for three consecutive years. Raptor community in the study area was diverse (13 species). Breeding of ornitophagous species such as Booted eagle <i>Hieraaetus pennatus</i>and Northern goshawk <i>Accipiter gentilis</i> was confirmed in the forest patches. We identified 10 grape-eating bird species, with Spotless starling (<i>Sturnus unicolor</i>) being the most abundant. Distance from the edges between vineyards and natural and semi-natural woody vegetation affected damage to grapes, with more damage close to the edges. The installed elements did not significantly reduce damage to grapes. Woody vegetation in and around the vineyards may reduce the success of the installed elements by providing shelter to grape-eating birds and suitable sites for raptor breeding and perching. Other variables such as vine orientation, land-cover, and distance to raptor nests did not affect damage to grapes. To promote the conservation of raptors and their regulating services in this Mediterranean agroforestry system, more research is needed to find methods to increase the presence of raptors in vineyards and to manage the woody shelters used by grape-eating birds around crops.

多种鸟类可对葡萄生产造成严重危害。猛禽（raptor）作为食葡萄鸟类的生物防治因子，其应用潜力目前尚未得到充分认知与推广。我们在西班牙中部的葡萄园搭建人工巢箱与栖架，以吸引猛禽在此栖息活动，并探究其降低葡萄因鸟类取食造成损害的效果。研究期间，我们通过野外调查与天然繁殖位点评估，对研究区域的猛禽群落进行了特征描述，同时评估了食葡萄鸟类的种群丰度，并连续三年对葡萄生产的受损情况开展采样监测。研究区域内的猛禽群落多样性较高，共计13个物种；林地块中已证实食鸟性猛禽物种的繁殖活动，例如靴隼雕（Hieraaetus pennatus）与苍鹰（Accipiter gentilis）。本次研究共记录到10种食葡萄鸟类，其中以纯色椋鸟（Sturnus unicolor）为种群丰度最高的物种。葡萄园与天然、半天然木本植被带之间的边缘距离会对葡萄受损程度产生影响，距离边缘越近，葡萄受损情况越严重。本次搭建的人工设施并未显著降低葡萄的鸟类取食损害。葡萄园内部及周边的木本植被，可能通过为食葡萄鸟类提供庇护场所、为猛禽繁殖与栖息提供适宜位点，削弱了人工设施的防控效果。其他变量例如葡萄种植行朝向、土地覆被类型以及距猛禽巢穴的距离，均未对葡萄受损情况产生显著影响。为在该地中海农林业系统中推动猛禽保护及其生态调控服务的发展，未来仍需开展更多研究，以探索提升葡萄园猛禽种群数量的方法，并管控农田周边食葡萄鸟类赖以栖息的木本植被。