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A new study in Frontiers in Ecology and Evolution suggests that birds have two alternative strategies to cope with the difficulties of humanity’s increasingly chaotic cities: having large brains or more frequent farms.
Surviving in cities is so difficult that many bird species can be brought to extinction by the growing urbanization of the world. But curiously, some birds face and thrive even in these new environments. Understanding which species are successful and which have no implications for conservation programs and also helps humans better understand which species they share their cities with.
“Cities are difficult environments for most species and therefore often support much lower biodiversity than natural environments,” explains postdoctoral researcher Ferran Sayol of the University of Gothenburg and the Global Biodiversity Center in Gothenburg in Sweden. “The species that can tolerate cities are important because they are the ones that most humans will come into contact with in their daily lives and can have important effects on the urban environment within our cities.”
Many previous studies have shown that birds with larger brains have numerous advantages. They can find new food sources and avoid man-made dangers better than birds with a smaller brain. But researchers have not yet been able to explain why some species with small brains, such as pigeons, can also thrive in cities.
To understand what allows birds to adapt to urban life, Sayol and his colleagues analyzed databases containing brain and body size, maximum lifespan, global distribution and reproductive frequency. They used existing museum databases and collections that contained details on over 629 bird species in 27 cities around the world.
Their results confirmed that brain size plays an important role, but it is not the only way to success.
“We have identified two distinct ways for bird species to become urban dwellers,” says Sayol. “On the one hand, species with large brains, like crows or seagulls, are common in cities because large brain sizes help them face the challenges of a new environment. On the other hand, we also found that small-brain species, such as pigeons, can be very successful if they have a high number of reproduction attempts during their lifetime. “
The second strategy represents an adaptation that privileges the future reproductive success of a species over its current survival. Interestingly, their research suggests that the two strategies represent distinct ways of dealing with urban environments because birds with an average brain size (relative to their body) are less likely to live in the city.
Not surprisingly, both strategies are less common in natural environments. Researchers are working to understand how these adaptations will change the behavior and structure of urban bird communities in the future.
Sayol’s study highlights that there are several strategies for adapting to urban habitats. When considering the impacts of our increasingly urban future on our wildlife neighbors, it will be important to consider both their reproductive strategies and their brain size.
“In our study, we found a general model, but in the future it might be interesting to understand the exact mechanisms behind, for example, which aspects of being smart are the most useful,” says Sayol. “Understanding what makes some species more capable of tolerating or even exploiting cities will help researchers anticipate how biodiversity will respond as cities continue to expand.”
Header image – Public domain
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