Harrow's pigeons should beware - they could soon suffer the fate of their Trafalgar Square counterparts.

Falconry is just one of the methods used by Andy Dobbs to rid Harrow's offices and homes of the flying pests.

Running the Harrow franchise of pest control company NBC, Andy Dobbs, of Kingsville Road, Hayes, uses Harris hawks to rid buildings of pigeon infestations. He says the process involves no cruelty: "Using hawks works, it's a natural way of preventing pigeons nesting in buildings. A couple of birds are fine, but once you have 50 or so breeding they become a health hazard to people and themselves.

"We never aim to hunt and any killings are purely accidental."

The hawks are introduced to the environment as predators, encouraging the pigeons to find safer roosting spots away from the infested building.

Andy has been working in Harrow and other boroughs since June 2007 but not everyone welcomes his services. "For every office building full of workers who hate pigeons, you get two who feed them on a regular basis and want to protect them. I've had a few people accusing me of cruelty - but I always tell them this is a very natural method," he says.

Andy is on a mission to persuade local authorities to sit up and take notice of this medieval form of hunting out vermin. "Some councils like Reading and Slough have a policy on counting pigeons as pests and will recommend us. Harrow Council don't have one on pigeons and so they won't help sort out any infestations," he says.

He adds that other local authorities are also slow to incorporate a pest control programme: "I know that Northwick Park Hospital has had trouble with pigeon infestations, but they don't get back to me. It's the same with a lot of NHS trusts."

It is difficult to house several birds of prey in a back garden without attracting attention, as Andy has found. "I say to my wife that I'm taking the birds for exercise in the park for an hour or so, but as soon as I get there people are getting their cameras out and wanting to talk to me. It's sometimes a good four hours later that I get home; the birds are like magnets. When I take them out, it's a little like walking your dog," he says.

Idyllic as the job sounds, caring for the working birds is an arduous task: "Every morning I have to check their faeces and their eyes for any signs of illness. Then they have to be weighed. The average life of a wild hawk is 12 years - when they're in captivity, we can provide them with antibiotics and a regular supply of food. Then they live for up to 25 years."

If a falconry response is necessary, Andy must pick his bird of prey with care: "There's no point using a great big eagle to hunt pigeons who have

nested in holes and nooks of buildings. An eagle is certainly a predator and would discourage pigeons from staying, but pigeons know that eagles are slow, cumbersome hunters. It's more effective to use a hawk which is able to turn and chase much faster. Equally in a landfill site, a snowy owl is more effective at hunting gulls. It's about understanding the relationship between birds and their prey.

"Some situations are too dangerous for our birds, like if there are pylons or loose wires around.

And their safety always comes first."

In spite of this caution, accidents still happen: "If you're working on a building site, the birds can get lost among all the machinery and you don't spot it until it's too late. There have been a few tears at home when a bird has gone missing. It could be for any number of reasons - maybe a dog has frightened it.

"One hawk I lost had a transmitter attached to it, but unluckily that didn't work. I think he's a permanent loss. Another went missing a week later, but he turned up in a friend's garden - that was sheer luck."

Birds of prey are accustomed to hunting in open fields and countryside, and keeping an urban bird clean is not easy: "My Harris hawk, Tony, has grey tail feathers, but the ones in Scotland are snowy white. It's the grimy surroundings - I've tried fairy liquid on him, but nothing cleans him up properly."