By Ella Davies

Earth News reporter

Urban birds are more resourceful

City dwelling birds have larger brains relative to their body size, according to scientists. They have found that family traits are key to identifying why certain birds thrive in European cities. "Urban adapters" including tits, crows, nuthatches and wrens all come from families of related species that have large brains compared to their bodies. Scientists suggest that larger brains make birds more adaptable to the changeable conditions of city living. ADAPTERS AND AVOIDERS Urban adapters included blue tits, magpies, nuthatches, wrens and long-tailed tits Species said to avoid cities included yellowhammer, reed bunting, whitethroat and pied flycatcher Researchers also identified small-brained exceptions that have found ecological niches in cities such as barn swallows and white wagtails

Watch crows with a unique city-centre method of cracking nuts Researchers from the Evolutionary Biology Centre, Uppsala, Sweden and the Donana Biological Station, Seville, Spain studied 82 species of birds from 22 families. Focusing on 12 cities in France and Switzerland, they aimed to find out why some species of bird are more successful in urban environments than others. Their findings are published in the journal Biology Letters. "We were interested whether behavioural flexibility can increase the chance of a given species to successfully colonise cities," explained evolutionary biology expert Dr Alexei Maklakov. "After all, a centre of a modern city is a novel and rather harsh environment for most species and the ability to sustain a varied diet or develop novel foraging techniques and perhaps utilise non-standard nesting places, can be beneficial." The researchers analysed the family trees of the species studied and found one key similarity. Birds breeding in city centres, or "urban adapters" as the team called them, were found to have larger brains relative to their body size. Previous studies have highlighted the link between larger brains and behavioural innovation in birds and mammals. Scientists say this new evidence is the first to show that brain size is a key factor for animals' survival in urban environments. Although some small-brained species, such as barn swallows, survive in cities they cannot be considered true "urban adapters" according to Dr Maklakov. Whole families of birds are less likely to adapt to novel conditions and if we want to see them in the cities we will have to create patches of their original habitat

Dr Alexei Maklakov

Evolutionary Biology Centre, Sweden "Some of [the small] brained species are lucky enough to find niches in urban habitats that are by coincidence a pretty good approximation of their original habitat," he said. Dr Maklakov suggests that the specific ecological niches which support small-brained species are exceptional and not typical of true urban environments. The team say their findings could prove useful for future conservation efforts. "[The study] suggests that some species and even whole families of birds are less likely to adapt to novel conditions and if we want to see them in the cities we will have to create patches of their original habitat," said Dr Maklakov.



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