TO THE ordinary human eye, these robotic peregrine falcons (see image) look like remote-controlled gadgets which might top many a youngster's Christmas list.

But to the real birds which pester buildings the world over, they are something altogether more sinister.

Robop, a Macmerry firm, has just celebrated 10 years of providing some of the world's best known firms in 15 countries with their large, life-like mechanical peregrine falcons.

The birds do not fly, but they sit high on buildings and structures, making random movements of their wings and heads and peregrine falcon noises - keeping problematic creatures like gulls and pigeons away.

Some of the companies to have ordered the birds include Caterpillar, The All England Tennis Club, Schiphol Airport in Amsterdam, B&Q, BMW, Liverpool City Council, Standard Life and the US Navy.

There are also Robop birds in more unusual locations - such as a German shipyard, offshore gas platforms and a salt mine in upstate New York.

Peregrine falcons are one of the most widely distributed birds of prey in the world. Their bodies usually measure about 15-20 inches, but Robop's mechanical birds can be up to 1.5 inches larger.

The bird was the brainchild of Bob McIntyre, who worked as a pest control expert. In 2003, Robop tried to develop a flying bird but without success. However, the firm believes its product to be one of the most effective pest control measures anywhere in the world.

John Donald, managing director of Robop, explained the concept: "There are other techniques to do the same job - people fly live hawks for instance, or they put nets and spikes on the roof.

"But these are big, open roofs and to put spikes on them is not practical, and to put a net up is very expensive - probably 10 times as costly as using one of our products.

"[The model] moves randomly, so it moves its head and its wings, and makes peregrine falcon calls.

"It does that in quite a sudden and random way. That really freaks the gulls or pigeons out.

"They see it straight away as a threat. If it starts to move, then they think, 'He's after me'. They will go away and come back with reinforcements, and they will fly down next to the peregrine and try to do anything to get it to move.

"When it doesn't move, they think, 'He's tough, he's not going to be scared', and they clear off." The birds are assembled at the firm's Satellite Park base by a team of four workers. A basic model costs about �3,000 plus VAT.