Air travellers are used to being grounded by the weather.

Fog, wind, snow and thunder can affect airline schedules but what about our feathered friends?

Few passengers will probably consider, as they're strapping themselves into their aeroplane seats, that birds can potentially hinder travel plans.

The reason travellers don't have to flap about it at Leeds Bradford International Airport is down to an invaluable service it introduced 15 years ago.

Bird control has been in operation since the Second World War. At one time airports dealt with it in-house but tighter regulations have demanded more expertise, which is why Gill Cree was drafted in.

Gill is the airport's bird control contractor. She has the rare opportunity of being able to take her pets to work as they are vital in helping her deliver a specialist service ensuring the safety of aeroplanes as they take off and land.

Climbing aboard her specially-equipped bird control van, Gill is greeted by her four-legged and feathered workforce. Meg the Jack Russell giddily clambers into her lap while Ellie the golden retriever settles into the passenger seat.

In the cab, Aero, a Peregrine falcon that Gill has hand-reared, and Professor Hooch, a cross between a Gyr peregrine and a Saker falcon, stand elegantly on their perches ready to start work clearing birds from the Yeadon airfield.

As soon as Gill has made contact, via radio, to the control tower to make sure the coast is clear of any arriving or departing planes, we head off to the far end of the runway. "We position ourselves where we can be of most use," says Gill.

Gill can work anywhere on the airfield. Her onboard communication and hand-held radio keep her in constant contact with the airport control tower so she and her animals, who have special airside passes, can work safely, without being a hindrance.

She has built up a rapport with local landowners and businesses on the airport periphery who assist her in her service by allowing her access on their land when necessary.

"We look at the whole area around the airport because it is controlling the bird hazard around the airfield, within the approaches and circuit," explains Gill.

She has trained her animals to work in a safe and controlled way. While the raptors (birds of prey) and the dogs are natural predators, their intention is not to kill the birds. Gill explains that the mere presence of the raptors in the sky and the dogs on the ground is enough to move on the lapwings and other birds that migrate here.

"We persuade them (the birds) that while the airfield appears to be a wonderful habitat it isn't and it is somewhere they don't want to be," says Gill.

But, as she explains, there is no quick fix solution as they are changing the habits of generations of birds. "We are moving the boundaries to persuade them there are nicer areas where they can feed and roost," she says.

Gill's expertise comes through experience. Her extensive knowledge of birds developed through a childhood love of nature. Being able to identify the types of birds in and around the airfield is imperative to her job but raptors are her real passion. "Once I was in a position to get one I learned about them and how to fly them and very quickly they took over my life," she says. "Then came the conflict between being with the birds and earning a living."

Gill started off doing falconry displays at country shows and she was also involved in a bird centre through which she was able to solve a specific problem for another airport. This led to her permanent role at Leeds Bradford International Airport.

"That is where it started and we have developed it since because the regulations have changed so much and they are now looking at getting a national standard for bird control," says Gill.

A big advantage is that her four-legged and feathered workforce have grown up at the airport. "The dogs were brought up here as puppies so they are used to working with an aeroplane flying over them.

"And the birds were also brought here as babies. A lot of birds we use are imprints, they are hand-reared on us," says Gill, referring to her business partner Malcolm Tyson.

As well as working at the airport, their business, NSF Wildlife Management also deals with bird control at feed mills and factories, which involves predominantly clearing pigeons.

The business is based at Gill's North Yorkshire farm, home to 26 hawks and falcons. Breeding and working with the birds means Gill and Malcolm are continually expanding their knowledge and developing their expertise in the specialised service.

"It's also about using the right tools at the right time," says Gill, referring to the bio-acoustical distress call she uses which, she explains, is a digital reproduction of the alarm calls of specific species.' Some birds aren't bothered by the call, which is why it's imperative to have a specialised service covering all consequences. "Nothing on its own will do the job effectivel. You have to use every weapon in the armoury but you have to use it appropriately," says Gill.

Andy Ormshaw, the airport's air traffic manager, says Gill's vital service is all part of the airport's active habitat management. He explains that the airfield grass also has to be kept to a certain length to deter birds from coming here to feed, and it must be tall enough to persuade small birds that they can't see their enemies coming.

"We have to keep the airfield very clean. We don't allow rubbish or anything loose which can do damage to the aircraft engines and people," says Andy. "The cost involved for one fodded' (Foreign Object Damage) engine caused by a bird strike would pay for bird control for years, so it makes economic sense apart from safety sense," says Andy. "It's a lot more than shooing birds off the runway. We need someone with expertise to control and deter birds and that is what Gill does. She has enormous expertise."

As part of their work at the airport, Gill and Malcolm have also built up a relationship with bird research charity the British Trust for Ornithologists, assisting in the construction of owl boxes which they constantly monitor.

Watching Gill at work while passenger jets roar off overhead, I wonder what her favourite holiday destination would be. Incredibly she tells me she and Malcolm work 364 days a year. They only get Christmas Day off!

I doubt they're too disgruntled though. Gill appears to be more than happy being at home with her animals than hopping off on a plane abroad. "Malcolm is probably worse than me. He has been around birds since he was 10 and he's totally addicted!" she laughs. "Everyone has a passion in life. My absolute passion is the Gos Hawk. There is something about them. They are so independent but when you get close to them they will accept you and you can be part of their life.

"It's such a privilege flying a bird of prey. It's as close to nature as you can get."