Urbanization and Bird Coloration: A New Study Reveals Surprising Findings
In 2016, Juan Diego Ibáñez-Álamo, a researcher at the University of Granada in Spain, collaborated with Kaspar Delhey, an expert in bird coloration at the Max Planck Institute for Biological Intelligence. Their study, published in Ecology Letters on April 4, 2023, is the world’s first large-scale, global study on how urban environments affect bird coloration.
The researchers analyzed color data from nearly all bird species around the world and found that urban birds that are able to lead fuller lives are also more likely to sport blue, grey, and black plumage. This finding challenges some long-held assumptions in urban ecology.
Breaking Through:
If you look at a city park, you may find fewer species than in a nearby forest. However, those species tend to be more colorful. The urban color homogenization hypothesis suggests that cities render bird colors more uniform, but the researchers found that once you account for species richness, cities actually have more color-diverse bird communities.
Being Seen is Dangerous:
Successful city birds are more likely to be colorful while avoiding brown. Brown colors are often found in species that live in the understory of forests, which is similarly colored. In cities, green spaces are different, often with more asphalt or concrete, which changes the brown background. Brown is considered a cryptic color, but it appears to lose its ecological value in human-built environments.
Urbanisation Filters Species:
Delhey said urban ecology is becoming a kind of evolutionary laboratory. As more species travel to parts of the world they haven’t been to before, the ways in which they’re adapting — from song pitch to feather hue — are offering researchers insights into their survival as much as life’s astonishing plasticity.
The new study has far-reaching implications. Cities are not just grey and lifeless; they host a different kind of avian beauty. As biodiversity declines in many parts of the world, the ecological and cultural values attached to urban wildlife become more significant. Understanding the patterns therein can help make cities more hospitable for a wider range of species.
Next Steps:
The next step will be to see whether other organisms, such as insects or mammals, follow the same patterns. Arthropods, he said by way of example, are tremendously diverse. "And they also suffer from a reduction in the city, in urban areas. It will be super-interesting to identify whether they follow the same patterns."
Monika Mondal is a freelance science and environment journalist.
