London's a real hoot after dark, say twitchers

London's nightlife will come under the spotlight in a novel way this summer when the public take part in a survey of the capital's owls.

One might not think of owls as city birds – but they penetrate right into London's heart. Berkeley Square in Mayfair, where the famous but imaginary nightingale sang in the song, has actually been the home of a real tawny owl. In fact, all five regularly breeding species of British owl can be found in Greater London, although two, the short-eared and long-eared owls, are visitors.

The beautiful white barn owl can be found as near the centre as Ealing. The little owl, which hunts in daylight, can be found in the leafier suburbs such as Willesden and Barnes, while the much commoner tawny owl can be found across all 32 London boroughs except for the City of London itself.

The survey, named Owl Prowl 2011, is to be launched in August by the London Wildlife Trust, a quarter of a century after a similar survey recorded 441 owls in London. They consisted of one record each for long-eared and short-eared owls, nine records for little owls, 12 for barn owls and more than 400 for tawny owls. On the basis of that survey, the trust estimated that London had about 100 tawny owl pairs. The new Owl Prowl, which is celebrating the trust's 30th anniversary, is calling on Londoners to record hearing or sighting any owls.

The purpose of the survey is to raise awareness of the city's owl populations and the threat they face owing to loss of habitat. The trust says that many city dwellers are unaware that these shy birds can be found in the capital, usually in tranquil wooded areas.

"Owls have always been present in London, but are rarely heard, let alone seen, by many," said the trust's director of conservation, Mathew Frith. "They have benefited from the improved management of many parks, and the growing maturity of the urban forest of garden trees and railway woodlands. Nevertheless, the loss of brownfield sites and of garden vegetation poses threats to their survival in the inner city."

Finding birds of prey in London is a lot commoner than it used to be. In the 1990s the sparrowhawk became a regular resident of the suburbs, following a course set by the magpie 20 years earlier, and in 1988 a survey of kestrels found that the hovering falcons were nesting in every borough, with a total of 400 pairs across London. The most spectacular birds of prey in the capital are peregrine falcons, with about half a dozen pairs. Three years ago, a pair nested in the Houses of Parliament.