Urbanization takes a bigger toll on bird diversity in the tropics than it does at other latitudes, study finds
Researchers at McGill University have found that urbanization is weakening one of Earth's most enduring ecological patterns: the tendency for biodiversity to increase toward the tropics, a pattern known as the latitudinal diversity gradient.
A new study reveals that urbanization is disproportionately undermining bird diversity in tropical regions compared to other latitudes. Researchers from McGill University analyzed bird populations worldwide and discovered that on average, urban areas near the equator had 42% fewer species than natural counterparts, while the global average was 32% fewer.
At a latitude of 65 degrees, this gap narrowed to 12%. The researchers attribute the larger loss to more intense urbanization in tropical cities and the inherent ability of tropical bird species to adapt to changing environments. Anna Hargreaves, the senior author and biology professor, emphasized the striking consistency of the latitudinal diversity gradient, which has persisted for tens of thousands of years, and now faces significant erosion due to urbanization.
The study, published in the Proceedings of the National Academy of Sciences, analyzed over 10,000 bird species across five continents using the citizen-science database eBird. While previous research on the latitudinal diversity gradient relied on smaller, localized data sets, this study's extensive analysis reveals that suburban areas and cities with ample green space experience smaller declines in bird diversity.
Ongoing research aims to understand how these changing patterns of diversity affect species interactions in urban environments, such as predation and pollination.
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