Worldwide, urban areas are spreading at massive rates. Simultaneously, urban agriculture is growing in importance. However, urbanization effects on functional biodiversity on farmland remain poorly studied, especially in urbanization hotspots of the global south. Here, we sampled birds on 36 farms across three seasons (one full year) and along two urbanization gradients in the Indian megacity Bangalore, using a paired site design to separate local and landscape effects of urbanization. At various spatial scales, including local and multiple landscape scales, we observed a consistent reduction in bird diversity as a result of urbanization. An increase of landscape-wide impervious surface area from 0% to 80%, lead to an average reduction of 50% of bird species and individuals, with open woodland species being the biggest losers. Invertebrate-feeding birds already experienced 60% losses with only 40% of impervious surface, particularly during the monsoon, i.e. the main cropping season, suggesting a great potential decrease in biocontrol services for farmland in urban areas. In conclusion, we documented high losses of farmland birds in an Indian megacity due to intense and rapid urbanization, which is generally little studied but can be currently observed in many other tropical countries.

在世界范围内，城市地区正在以巨大的速度扩张。与此同时，都市农业的重要性日益增加。然而，城市化对农田功能性生物多样性影响的研究仍然很少，尤其是在全球南方的城市化热点地区。在这里，我们在印度特大城市班加罗尔的三个季节（一整年）沿着两个城市化梯度对 36 个农场的鸟类进行了采样，使用成对的场地设计来区分城市化的局部和景观影响。在各种空间尺度上，包括局部和多重景观尺度，我们观察到由于城市化，鸟类多样性持续减少。景观范围内的不透水表面积从 0% 增加到 80%，导致鸟类物种和个体平均减少 50%，其中开阔林地物种是最大的输家。以无脊椎动物为食的鸟类已经经历了 60% 的损失，只有 40% 的不透水表面，特别是在季风期间，即主要的农作物季节，这表明城市地区农田的生物防治服务可能会大大减少。总之，我们记录了印度大城市农田鸟类因强烈和快速的城市化而大量流失，这通常很少被研究，但目前可以在许多其他热带国家观察到。