By Alex Kirby BBC News Online environment correspondent

Birdlovers in the UK have found a hi-tech solution to the perennial problem of egg stealing.

These thieves will try anything to steal the eggs

Tom Austin, RSPCA

They are marking new-laid peregrine falcon eggs with a dye which in normal conditions is virtually invisible.

The dye, known as SmartWater, will also be used for marking the chicks once they have hatched.

The technology already has a number of prosecutions to its credit.

The scheme will run in Shropshire, in the English Midlands. It is a joint operation by the Royal Society for the Prevention of Cruelty to Animals (RSPCA) and the Shropshire Peregrine Group (SPG).

Raiders face frustration

It also involves keeping one persistently targeted peregrine nest in the south of the county under surveillance. Thieves have raided the nest every year for the past decade.

Tom Austin of the RSPCA said: "These thieves will try anything to steal the eggs. However, we are determined to protect them and see that the baby peregrine falcons emerge from their nest unscathed this year."

Peregrine falcon: Nesting sites are under surveillance

John Turner of the SPG said volunteers had watched the nest and 13 other peregrine nesting sites around the county to ensure the eggs' safety.

He said: "This nest is particularly vulnerable, and we are pleased to be working with the RSPCA to protect these eggs.

"It has been very disappointing for the thieves to be successful for so many years. Hopefully the investment in SmartWater will now bring an end to their illegal looting."

SmartWater, which has made possible the conviction of more than a hundred offenders, is a clear, non-hazardous water-based solution.

SmartWater has many uses

It is painted on the eggs and chicks, and in normal conditions is virtually undetectable. But it is clear to see under ultra-violet light.

It cannot be removed, and the liquid is encoded forensically with a unique identification number that will identify any stolen eggs or chicks.

Posters are being put up around the nesting site to warn intending thieves of the risk they run.