中文导读 城市鸟种少于周边自然区并不新鲜，但麦吉尔与 ETH Zurich 团队用逾 1 万种鸟、五大洲 eBird 记录发现：从两极到热带的纬度多样性梯度在城市中约弱三倍。总体城市约少三分之一鸟种（约 32%）；赤道附近约少 42%，高纬约 65° 仅约 12%。热带更多栖息地专化种，城市偏爱广适种，专化种不成比例缺失；同纬度绿地更丰富的城市留种更多。综述见 The Conversation 2026-11-03，研究刊于 PNAS。阅读时可留意 overall、roughly、yet、rather than proving 如何保留格局描述与因果边界。
正文 Cities around the world hold fewer bird species than nearby wild places , but a new global study says the loss is far sharper near the equator . Researchers from McGill University and ETH Zurich analysed sightings of more than 10,000 bird species and found that the familiar rise in diversity from the poles to the tropics is about three times weaker in cities than in natural areas . Their summary appeared on The Conversation on 3 November 2026, after related findings in the Proceedings of the National Academy of Sciences .
本段译文 世界各地的城市里鸟类种类通常少于附近的自然区域，但一项新的全球研究显示，赤道附近的损失远更明显。麦吉尔大学与苏黎世联邦理工学院的研究者分析了逾 1 万种鸟类的观测记录，发现从两极到热带多样性递增这一常见格局，在城市里大约只有自然区域的三分之一那么强。作者在 2026 年 11 月 3 日于《The Conversation》发表综述，相关发现此前刊于《美国国家科学院院刊》（PNAS）。
The pattern is known as the latitudinal diversity gradient : life tends to grow richer toward the tropics . Urbanisation replaces wetlands , forests and other habitats with pavement , buildings and similar lawns from the Arctic to the equator . Earlier work already showed that cities often cut local diversity . The new question was whether that local damage also reshapes a global pattern that has lasted for millennia .
本段译文 这一格局被称为纬度多样性梯度：生命往往越靠近热带越丰富。城市化用路面、建筑和相似的草坪，从北极到赤道取代湿地、森林等栖息地。早前研究已表明城市常会降低本地多样性。新问题是：这种本地损失是否也在改写一条延续千年的全球格局。
Comparing one - square -kilometre cells , the team found cities had about a third fewer bird species than natural areas overall , or roughly 32 percent fewer on average . Near the equator , an urban cell averaged 42 percent fewer species than a natural cell at the same latitude . At about 65 degrees latitude , the gap shrank to roughly 12 percent . In other words , tropical cities lost about three times more diversity than high-latitude cities . Examples used in the authors summary include Singapore or Quito versus Reykjavik or Fairbanks .
本段译文 团队比较了一平方公里网格：城市总体比自然区域大约少三分之一鸟种，平均约少 32%。靠近赤道时，城市网格比同纬度自然网格平均少 42% 的物种；大约在北纬或南纬 65 度，差距缩到约 12%。换言之，热带城市失去的多样性大约是高纬度城市的三倍。作者综述中的例子包括新加坡或基多，对比雷克雅未克或费尔班克斯。
One reason lies in who lives where . Tropical bird communities contain more habitat specialists that depend on particular plants , insects or forest structure . Cities tend to favour generalists such as crows and Canada geese . The study found specialists were disproportionately missing from urban checklists , which helps explain the deeper tropical losses . Greener cities at the same latitude kept more bird species than harder , more paved cities , a hopeful signal for planning
本段译文 一个原因在于谁住在哪里。热带鸟类群落含有更多依赖特定植物、昆虫或森林结构的栖息地专化种。城市往往更利于乌鸦、加拿大雁这类广适种。研究发现专化种在城市观测清单中不成比例地缺失，有助于解释热带损失更深。同纬度下，绿地更多的城市比硬质铺装更多的城市留住了更多鸟种，这对规划是一个有希望的信号。
The analysis drew on millions of eBird records from birdwatchers across five continents plus data on population density and land use to label cells as urban , suburban or natural . Only cells with enough checklists were kept so that rich tropical sites were not unfairly undercounted . Sensitivity tests pointed in the same direction . Lead voices include Anna Hargreaves and Jennifer Sunday of McGill . The authors note that urban green space may soften diversity loss for both wildlife and people , yet the work describes patterns rather than proving that one design will restore every missing specialist
本段译文 分析依托五大洲观鸟者提交的数百万条 eBird 记录，并结合人口密度与土地利用数据，把网格标为城市、郊区或自然。只保留清单足够多的网格，以免物种极丰富的热带地点被低估。敏感性检验指向同一方向。主要作者包括麦吉尔大学的 Anna Hargreaves 与 Jennifer Sunday。作者指出，城市绿地或许能减轻对野生动物和人的多样性损失，但这项工作描述的是格局，并不能证明某一种设计就能让每种缺失的专化种都回来。
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