New study reveals fascinating difference between city birds and their rural counterparts: 'More common in natural environments'

Birds that thrive in city environments "exhibit more elaborate colors" than their rural counterparts, a new study has found.

What's happening?

ZME Science recently reported on a new study published in the journal Ecology Letters that looked at nearly 1,300 bird species using a global database to analyze the colors of their plumage.

The team of researchers at the University of Granada and the Max Planck Institute for Biological Intelligence found that birds that do well in urban settings are more likely to have feathers that are "blue, dark grey and black, and less likely to be brown or yellow." Those that thrive in more natural habitats tend to be shades of brown. 

"Our findings suggest that plumage colours are part of an urban-associated syndrome," the co-authors wrote. Or, as ZME Science noted, these patterns "likely [tie] into how city life shapes animal behavior and appearance."

Researchers are unsure of the exact causes, but they have some thoughts. Plumage color can support a bird's ability to regulate body temperature, hide from predators, and find mates, so shifts in that color may relate to these aspects of survival.

In a statement, co-author Kaspar Delhey explained, "Brown shades are more common in natural environments than in cities. We suspect that brown birds are at a disadvantage in a rather gray city." Urban environments tend to be packed with concrete, asphalt, artificial light, and industry while featuring fewer green and woody spaces than neighboring suburban and rural areas. 

All of that concrete and construction can drape cities in various grays with pops of less-than-natural colors. Birds that historically have been more brown may have adapted in cityscapes to be less visible there — and less vulnerable to potential predation — against a changing backdrop.

On the other hand, cities are also typically home to fewer traditional predators overall. If city birds are less vulnerable to being seen and stalked by wild animals, camouflage may be less important than a colorful, elaborate costume that could be used to help birds find each other. As Earth.com posited in a summary of the study, "colors that once would have been risky may now help with recognition, mating, or dominance within species."

Why is this important?

Although this study shows that some birds may adapt to evolving urban surroundings, the reasons behind these shifts could still be concerning.

As humans continue to build sprawling homes and huge buildings in areas that were once habitats conducive to wildlife and as global temperatures continue to rise, many animals are responding with changes to key characteristics and behaviors. This has the potential to alter life in delicately balanced ecosystems and with unintended consequences. 

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Chemical, noise, and light pollution have been found to impact zebrafish activity. Declining populations of chimpanzees have lost vital mating gestures. And the changing migration patterns of humpbacks in Arctic waters, related to rising temperatures, may be causing the whales to compete with bowheads for food sources. 

What's being done about this?

The new study described in Ecology Letters seemingly runs at least somewhat counter to research that came out of China in 2024. That study found that urban bird species had darker and duller plumage than their rural counterparts, with researchers believing the duller colors could be due to toxic chemicals.

Clearly, more research is needed to better understand the potential connections between plumage colors and urban environments around the world. In the meantime, more actions can be taken to protect birds everywhere. 

An estimated 3 billion birds have been lost in North America since the 1970s, and more than 1,400 bird species have gone extinct. 

Organizations such as the National Audubon Society and BirdLife International welcome new members who want to help fight for the world's birds. But individuals can also make a difference by helping to reduce the impacts of human-caused pollution on the environment. 

Switching to solar power or making your next car an electric vehicle can help to cut the heat-trapping emissions that drive rising temperatures while saving consumers money in the long run. Learning about candidates who support pro-climate policies has the potential to do even more.

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