By Natalie Parletta
It’s not just big brains that can give birds a survival advantage in harsh urban environments. European researchers have found that some cerebellar birds, like the ubiquitous pigeons, maintain their parentage by breeding more.
The result, published in the magazine Limits in ecology and the environmentsolves the riddle of contradicting evidence for popular theory that birds need a large brain to achieve greater behavioral flexibility in coping with cities.
“We thought there might not be a single way to be a city dweller,” says lead author Ferran Sayol from the University of Gothenburg in Sweden, “and we found it.”
Many birds are threatened with extinction due to the increasing urbanization of the world, while others adapt and even thrive. Understand why this could help improve the dwindling biodiversity in cities and give insight into our feather-light neighbors.
“Urbanization is one of the most extreme environmental threats to biodiversity and is associated with high fitness costs for most organisms, with the population shrinking or the local population becoming extinct,” say Sayol and colleagues.
“For species that can take advantage of these new environments, cities offer a potential cornucopia of opportunities that allow an increase in abundance that goes well beyond that found in natural habitats.”
However, the birds that sit on telegraph wires and watch people scurrying through the cities with their song and decorating them are exceptional and could have a disproportionate impact on the health and well-being of people living in the city.
To learn their survival tactics, the researchers searched databases and museum collections for information in 27 cities around the world about the brain size (relative to body) of 627 birds and their maximum lifespan, global distribution, migration patterns, and breeding frequency.
The results confirmed that brain size played a role in urban success stories, but depended on their reproductive strategy.
Birds that produce few breeds in their lifetime are only successful in cities if they have a large brain. This includes the American kestrel (Falco Sparverius) and some tits, like the black-headed tit (Poecile atricapillus).
At the other extreme, species that have a smaller brain but give birth to many babies, including pigeons, black pigeons (Columbidae) and swifts (Apodidae), also perform surprisingly well in cities, suggesting that they will have future reproductive success of their kind prioritize before their current survival.
“Although these combinations of features are relatively uncommon in nature, they appear to be preferred in urban environments,” the authors write, “which leads to a remarkable restructuring of bird gatherings in cities.”
The findings could help control protection in urban landscapes, says Sayol, especially for average-sized birds who are least tolerant of urban environments.
“For example, if we wanted to increase biodiversity in urban areas, one solution could be to try to make it greener or to create corridors to the neighboring forest so that fewer breeding / cerebellar species can live in our cities. “