How birds survive city life by singing to a different tune

Even worse, many city dwellers often complain about how hard it is to meet members of the opposite sex.

However, there's at least one former inhabitant of the countryside who's coping rather well with all these stresses of urban life - the Great Tit.

The little bird has done this by changing its song. Typically those that live in cities and towns attract a mate with a call that is shorter, faster and at a higher frequency so they can still be heard above the din of traffic.

Experts say the discovery may help explain why some bird species thrive in an urban world, while others have no choice but to flee to the countryside for some peace and quiet.

The findings of a study - published in the journal Current Biology - looked at the habits of the Great Tit in ten major European cities including London, Prague, Paris and Amsterdam.

The bird, with its green and yellow plumage, glossy black head and two white cheeks, is traditionally a woodland species.

However, the five-and-a-half inch tit has proved it can adapt well to urban life and is now found throughout towns and cities.

Currently there are thought to be more than 1.7million pairs in the UK. As well as being easy to spot in gardens and parks, they can often be detected through their distinctive call which has been likened to a squeaky wheelbarrow wheel.

Experts say it sounds as if they are saying 'tee-cher tee-cheer'.

Scientists from Leiden University in the Netherlands wanted to find out whether the song may have adapted as the bird's environment has changed.

To do this they studied the song of birds in urban areas and compared it with that of the same species in nearby woodland.

They found that, overall, the songs used to attract a mate and to defend territory were shorter and sung faster in towns than in woods.

The urban songs were also at a higher frequency - probably to compete with low-frequency background noise such as that generated by traffic.

Lead researcher Dr Hans Slabbekoorn says his findings support the theory that animal species adapt their methods of communication to their environment.

The consistency of the results suggests that change in an inevitable part of being able to survive in modern European cities and so may explain why some species are unable to cope with urban areas while others adapt well to city life.

'The birds have to be able to adjust to their environment,' he said.

'They must have evolved in their first environment to be able to adjust to new neighbourhoods and this has now given them the capability to adjust to new noise such as that from traffic.'

His study looked only at the Great Tit.

But other research has suggested that different birds with equally broad vocal ranges may have similar abilities.

'I definitely think not all birds are able to do this but we do have some data to suggest that quite a few other urban survivors have the same traits,' he said.

He called for more research on both thriving and threatened species to see what role song-learning abilities may play.

'Such knowledge may become critical for conservation efforts that aim to prevent a division between those species that can make themselves heard and those whose songs drown in the urban rumble,' he concluded.