Pretty boy invasion

The squawk of parrots could soon drown out the traditional birdsong of the English country garden.

Experts say the wild parrot population has exploded, with numbers expected to reach 100,000 by the end of the decade.

Ring-necked parakeets that have escaped or been released by their owners are building thriving colonies in parks and gardens.

Because the species is robust and highly adaptable, it can survive our winters - and numbers are now increasing by 30 per cent every year.

The parakeets are also thought to benefit from the shorter, milder winters of recent years.

The brightly- coloured birds, more used to the tropics of Africa and Asia, have adapted so well to the British countryside that they could even start to ruffle the feathers of native birds.

There are fears that established species such as starlings, jackdaws, kestrels and little owls could suffer as the more aggressive parrots muscle in on them.

Wild parrots currently number around 20,000 in Britain, it is thought.

Dr Chris Butler, of Oxford University - one of the foremost experts on the wild parrot population - said it is now too late to stop their spread.

Dr Butler, who has just completed a four-year study of their spread, added: 'It might have been possible when there were a thousand or so of the birds, but there are just too many of them now. It had been thought that their numbers were growing very, very slowly.

'But I have discovered that the number of parrots is actually increasing by 30 per cent every year. It is a phenomenal rate.'

One roost in Esher, Surrey, is home to 6,900 of the birds.

There are other colonies all over the South East of England and Dr Butler said there are at least 10,000 in London alone.

They have also been spotted in Wales and are gradually spreading across the entire country, with sightings in Merseyside, Hull and as far north as Glasgow.

Originally, the parrots flourished in the suburbs because they relied on food put out in bird-feeders to survive. But Dr Butler has found them living in the countryside surviving on fruit, nuts, berries, seeds and tree buds.

There are also concerns that as their numbers swell, the parrots will begin to inflict widespread damage on farmers' crops.

One vineyard in Southern England was recently so hard hit by the birds, which are particularly partial to fruit, that wine production fell from 3,000 bottles to 500.

Because the parrots are protected under the Wildlife and Countryside Act, they cannot be destroyed without a licence. Parakeets have been popular pets since Victorian times and over the years many have escaped or been deliberately released.

Other reasons for the spread of the birds may have more to do with urban myth than reality.

It has been claimed that there was a mass breakout from a quarantine holding pen at Heathrow.

Others are said to have been released during filming of the 1951 Humphrey Bogart film The African Queen at Shepperton Studios in West London, or during the making of another film there in the 1970s.

Wherever the birds have come from, Dr Butler's research has revealed that they are breeding much faster than previously thought. Rather than rearing just one chick a year, he found they actually produce two. Because parrots can live for up to 34 years, it means each female could produce some 60 offspring.

Dr Butler also discovered that male parrots are reaching sexual maturity at the age of two, a year earlier than was thought possible.

Coupled with high rates of breeding, their territorial expansion means native species could come under intense pressure.

The balance is further shifted by the fact that the parrots nest - generally in holes in trees and other birds' nests - a month earlier than British birds, so allowing them to claim the best sites.