Mr Hallgarth is a falconer. It is early morning in Perthshire and he is out hunting with his prize flier - a five-year-old Bonelli's eagle called Savanna. She stands almost 2ft tall, weighs six pounds, and uses her 5ft wings to swoop down on to her prey at speeds of up to 90 miles an hour.
At today's meet the quarry is not foxes, nor grouse, nor deer but rabbits and hares, flushed out by spaniels and ferrets. Savanna is not alone. A group of visitors have paid more than pounds 100 a head to watch her kill. There's Barry the car dealer from Perth, Margaret the lawyer from Dunblane, and Ray, the double-glazing salesman from Glasgow.
Some 4,000 years after falconry, the sport of Emperors, was invented, the sharp, dark eyes and bright yellow beaks of birds of prey have become the new face of hunting in Scotland. Walking or riding to raptors is seen as a socially acceptable way to kill for fun. This "bloodsport for all" is now one of Scotland's fastest-growing outdoor pursuits.
When he started his firm, Lands of Finderlie, two years ago on a farm near Perth, Mr Hallgarth, 27, was one of a handful of commercial falconers north of the border, mainly located in the Tay valley and Gleneagles. Now there are more than 1,000 registered hawk keepers and this year alone the number of people paying to hunt with eagles and hawks on the Duke of Atholl's estate, where Mr Hallgarth works, has quadrupled.
"People love the birds and more are coming out to watch them all the time," Mr Hallgarth said. "We give them a chance to see something unique - birds of prey flying and killing in the wild. Our customers aren't the `hunting, shooting and fishing' types. They come because, like us, they admire the beauty and power of the raptors."
Falconers insist that hunting with birds is politically correct slaughter. At a time when bloodsports are under threat of extinction, that, they say, is the secret of the sport's success. Gerard Eadie, a businessman who runs Lands of Finderlie with Mr Hallgarth, explained: "It's natural, so no one can object. The birds would kill rabbits like this if they were living in the wild. All we are doing is providing a human audience. Where's the harm in that?"
Customers and the Royal Society for the Protection of Birds agree. Margaret Gimblett, a sheriff from Dunblane, "takes every opportunity" to head for the Atholl hills with Savanna and her keeper. "I would not go fox hunting," she said at last week's meet. "That's just a bunch of humans with dogs ganging up on a defenceless animal. But this is different. Sure, the rabbit dies, but it is a quick death and a natural one. I love it."
Under its royal charter, the RSPB adopts a neutral stance on field sports. But David Mitchell, the organisation's Scottish representative, has "no qualms" about hunting with raptors. "If the birds are bred safely in captivity and hunt in the wild, there is no bird conservation issue at stake," he said.
Others, however, are not so sure. Earlier this year the League Against Cruel Sports launched a campaign against falconry. Kevin Flack, the group's campaign manager, said: "Killing for sport is immoral. However natur-al, falconry is wrong and should be banned. We would urge people to boycott all meets where birds kill for entertainment. It may be long-established but the same is true of badger-baiting and cockfighting. Those practices are now illegal and soon, we hope, falconry, the forgotten bloodsport, will be, too."