Once a year, as they and previous generations have done for the last century-and-a-half, the farmers gather the strays until the sound of bleating on the hillside has been silenced.
Last Saturday the final part of the round-up operation began when more than 100 sheep which had been taken to the wrong farms were ferried by trailer or Land Rover to a farm yard opposite the 17th- century Bull's Head pub in Craswall.
The annual Shepherd's Day event always occurs on the second Saturday in July and has centred on the pub for 150 years - almost doubling the village's population of 170. Last weekend's gathering marked the end of an era.
Clusters of hill farmers gather in the yard to collect their animals beneath the steeply sloping mountain made famous by Bruce Chatwin's best- selling novel On The Black Hill, which portrayed the isolation of farming life in the area.
"It's quite an experience," said Colin Vaughan, 40, who rode his horse, Jasper, in the round-up and took the sheepdogs Spot and Floss to help bring 1,000 ewes back to Lower Maestorglwydd Farm, Llanigon, where he was born.
"There are so many hollows and dingles and fewer people to cover the hills these days," he said. "You must have good dogs and know what you are at. Most sheep don't move far and spend all year grazing their own patch but it's the ones who wander who cause problems.
"There was a time when everybody used to keep a few sheep but the little holdings are no longer viable and only a quarter remain.
"It's a lot of work and you have to be dedicated. It isn't a job you can half do. You either have to be interested or give up. When I was a kid the fern used to stop at the bottom of the hill. Now its three- quarters of the way up. If there were more sheep, they would curb it."
Once the hardy hill sheep - mostly Welsh mountain, hill Radnor and speckled face - have been brought home, the farmers have three days to verify the ownership of every animal by checking its ear tag.
Each flock is marked with the farmer's unique registered pattern which is displayed in the district's very own earmark book. By these the farmers can know, and reclaim, the missing members of their flock.
The work done, these shy, weather-hardened men settle down in the pub to relax and enjoy their social highlight of the year.
"I first came here as a trekker when I was 13 and it's a terrific get-together," said Madeleine Pritchard, 50, a sheep breeder .
"It can start very seriously. Until the ice is broken the pub looks more like a dentist's waiting-room.
"But these people have a sense of humour and companionship you don't find anywhere else. They are so independent and live in such a separate, close-knit community.
"There's no way they could bring their own flock down off the hills single- handed - it can't be done any other way."
Ron Gane, 60, a hill farmer, casts his expert eye over ewes in the yard, looking for two notches above a swallow-tail shape cut into the left ear of his sheep which distinguish them from the rest.
"With everybody coming from all around, the knowledge of earmarks is incredible," Mr Gane said.
"Only a small handful of sheep don't get claimed and they are eventually sold at Abergavenny market. The money is pooled and goes into the grazier's fund for mending bits of fence and mountain gates.
"This is the be all and end all of the shepherd's social year. In the old days they would ride over the hills on horseback, have a skinful of beer and then the horse would carry them home.
"There were all sorts of daredevil games like jumping the highest hedges and trying to stay on bucking bronco ponies that had never previously been ridden.
"The drink-drive laws have curbed it - but this is still a special occasion."
This weekend also marked the end of an era for Beattie Lewis, 72, who has been the licensee of the Bull's Head for 48 years. Her family have run the pub since two brothers travelled up from Somerset in the 1870s to repair Craswall's church bells - and one stayed on to run the Bull's Head.
Now, following the death of her husband Wilfred, Mrs Lewis has sold the pub and will retire later this month to a bungalow 12 miles away. Some farmers fear they may have witnessed the pub's last Shepherd's Day.
Geoffrey Howells, who keeps 800 sheep at Town Farm, Craswall, said, "People used to buy a lot of sheep down at Brecon and when they came here they would scatter because they didn't know their own mountain. But nearly all the sheep here today are home bred and they don't stray far.
"We don't know any other life. It's what we are reared for. When you are up there at 6am and the sun comes out it's the most beautiful place in the world and very peaceful too. Beattie wanted to be here today for her last Shepherd's Day. She will miss it when she goes."Reuse content