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麦吉尔大学2026年10月14日通报的研究发现：城市化正在削弱“越靠近赤道生物多样性越高”这一古老生态格局。全球城市鸟类物种平均比自然区域少约32%，赤道附近差距可达42%。专性物种流失与更强的城市开发是重要原因；保留绿地的城市损失较轻。本文讨论城市扩张如何改写全球鸟类多样性地图。

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Why do cities near the equator lose a larger share of birds than cities farther north or south? On October 14, 2026, McGill University reported a study published in the Proceedings of the National Academy of Sciences. The team found that urbanization is weakening one of Earth’s oldest ecological patterns: the rise in biodiversity toward the tropics. That pattern, called the latitudinal diversity gradient, has shaped life for tens of thousands of years. The new work asks whether local city effects can change that global map.

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靠近赤道的城市，为什么比更高纬度的城市失去更大比例的鸟类？2026年10月14日，麦吉尔大学通报了一项发表于《美国国家科学院院刊》的研究。研究团队发现，城市化正在削弱地球上最古老的生态格局之一：生物多样性向热带递增。这一格局被称为纬度多样性梯度，已塑造生命数万年。新研究追问：局部的城市影响能否改写这张全球地图。

Using eBird, a citizen-science database from Cornell University, the researchers examined more than 10,000 bird species across five continents. They divided the world into one-kilometre grid cells and kept only cells with enough records to capture at least 95 percent of local diversity. Each cell was labeled urban, suburban, or natural, based on population density and landscape change. Globally, urban areas held about 32 percent fewer species than nearby natural areas — roughly 95 versus 141 species per square kilometre in one summary. Near the equator the gap grew to 42 percent; at about 65 degrees of latitude it shrank to roughly 12 percent.

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借助康奈尔大学的公民科学数据库 eBird，研究者检视了五大洲逾一万种鸟类。他们把世界划成一公里见方的网格，只保留记录足够、能覆盖当地至少95%多样性的格子。每个格子按人口密度与景观改造程度标为城市、郊区或自然。全球来看，城市区域的物种平均比附近自然区域少约32%——一份汇总中约为每平方公里95种对141种。赤道附近差距升至42%；大约北纬或南纬65度处则缩至约12%。

As a result, the latitudinal diversity gradient was about three times weaker in cities than in natural landscapes. From high latitudes to the equator, mean diversity more than doubled in natural areas, but rose only about 36 percent in urban ones. Lead analyst Jory Griffith, a graduate student, and senior author Anna Hargreaves, a biology professor at McGill, say two forces help explain the pattern. Tropical bird communities include more specialists with narrow habitat or diet needs, and those specialists are more easily shut out of cities. Tropical cities themselves also tend to be more intensely urbanized, with less greenspace on average.

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结果是：纬度多样性梯度在城市中大约只有自然景观中的三分之一那样陡。从高纬度到赤道，自然区域的平均多样性增加一倍以上，城市区域仅上升约36%。主导分析的研究生 Jory Griffith，以及麦吉尔大学生物学教授、资深作者 Anna Hargreaves 认为，有两股力量有助于解释这一格局。热带鸟类群落包含更多栖息地或食性需求狭窄的专性物种，而这些专性物种更容易被城市挡在门外。热带城市本身也往往城市化更强，平均绿地更少。

Suburban areas and cities that keep substantial green space showed milder losses. The pattern held across hemispheres and seasons, which strengthens the authors‘ confidence. The study does not claim that every tropical city is doomed, or that parks alone can restore the old gradient. It does suggest that how cities grow can reshape one of ecology’s most familiar global signatures. Hargreaves calls preserving green space a hopeful measure that may let birds and people share urban land. The team next wants to learn how changing city diversity affects interactions such as predation and pollination — questions that matter for both wildlife and the services cities quietly rely on.

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郊区以及保留大片绿地的城市，损失较轻。该格局在南北半球与不同季节都成立，增强了作者的信心。研究并不声称每个热带城市注定无望，也不认为单靠公园就能恢复旧有梯度。它提示：城市如何扩张，可能重塑生态学中最熟悉的全球印记之一。Hargreaves 把保留绿地称作一种有希望的措施，或许能让鸟类与人共享城市土地。团队接下来想弄清城市多样性变化如何影响捕食、授粉等相互作用——这些问题既关乎野生动物，也关乎城市悄悄依赖的生态服务。

新闻来源

• McGill Newsroom · Urbanization takes a bigger toll on bird diversity in the tropics than it does at other latitudes, McGill study finds (14 Oct 2026)
• PNAS · Urbanization weakens the global latitudinal diversity gradient in birds (DOI: 10.1073/pnas.2527860123)

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