Sleeping on the moors in a round-the-clock guard is a sign of the devotion of the area's bird enthusiasts. John Dean meets two men fighting to proctect Northern England's most endangered birds - the hen harriers.

THE birds emerge without warning, gliding noiselessly over the heather moor, things of great beauty and elegance. Having stretched their wings, the hen harriers alight to preen themselves in the mid-afternoon Sun, mercifully unaware that they are the most endangered birds in Northern England.

Watching from the other side of the valley, at a secret location on the Geltsdale nature reserve not far from the Northumberland/County Durham border, are two men who have spearheaded a round-the-clock campaign to ensure that the juveniles, already large birds of prey but still only chicks, survive the summer.

For former Darlington fireman Phil Curtis and ex-soldier John Olley, the sight of the birds never fails to excite. Employed by English Nature, they have led a team which has camped out on the moor since May, spending pitch black nights in sleeping bags just metres from the nest, constantly training their telescopes and binoculars on the birds, and walking many miles on patrols.

To understand why all this effort has been made, a brief history lesson is necessary. In 1954, hen harriers recolonised the northern uplands after being wiped out by gamekeepers a century before when such persecution was still legal.

They are still persecuted and the reason is simple: many landowners and gamekeepers who do good work to preserve wading birds such as lapwings, golden plover and curlew and even birds of prey like merlin, detest hen harriers because each grouse they take is lost profit for shooting estates.

Few birds evoke such vigorous debates: landed interests blame illegal egg collectors and predation of eggs by creatures such as fox for the decline, conservation organisations say gamekeepers, and the landowners whose orders they follow, are the reason.

Whatever the reason, last year hen harriers failed to breed in the North-East for the first time since 1954 and in April this year, English Nature, the Government's conservation arm, launched a national rescue project, working with the RSPB, other conservation organisations, landowners and gamekeepers.

The project has allowed the birds to begin a national comeback: English Nature has just announced 11 nesting attempts in England, seven successful: in 2000 there were just five successful nests out of 13 nesting attempts nationally and last year was just as bad.

Of the 21 chicks produced this year, eight are in the region, six from one nest at a secret Yorkshire Dales location and two from Geltsdale. John and Phil have been responsible for monitoring both sites but the bigger effort has been at Geltsdale, a RSPB reserve a few miles north of Weardale in County Durham, surrounded by private land and in an area with a record of failed breeding attempts amid claims of persecution.

Phil, 44, who left the fire service four years ago after a back injury, and John, 39, an ex-Army chef, both live in County Durham, are members of Durham Bird Club and have witnessed disappointment as well as joy this year.

This spring a number of females appeared at Geltsdale but there was just one nest, and that failed when its six eggs vanished: the English Nature duo say there was no sign of attack by animal predators.

Then when it seemed that hope was fading, a second nest was discovered nearby and 24-hour protection begin in May, undertaken by the English Nature team supplemented by six RSPB workers and six local volunteers.

The chicks, now learning to fly and hunt for themselves, have been tagged so they can be constantly radio tracked and so far the signs are good.

Phil said: "Once you have seen male hen harriers 'sky dancing' you will never forget it, it is an amazing sight. We still get excited every time we see the young birds. To be honest, it is the kind of job I would have done for nothing just to see the birds.

"It has been hard work and has meant sleeping out on the moors, lying in the heather just 20 yards from the nests. The birds must have known we were there. However, we have tried not to disturb them and are delighted that the two young harriers have survived. People have given up their weekends and days off to dedicate themselves to ensuring that these birds are a success."

English Nature has placed great emphasis on working with landowners and gamekeepers but at Geltsdale has used new measures in the Countryside and Rights of Way Act to gain access to some areas of private land to monitor the birds.

Phil is acutely aware of the creature's troubled history but said: "I have no axe to grind with shooters or gamekeepers - they are doing a professional job and shooting is a business - but there must be room for everything to live in harmony."

John Olley said the close-knit protection team had worked well together and added: "It has been an absolutely fantastic experience working with the birds but also working with the people as well."

He believes that if the birds become re-established on Geltsdale, they could head south, saying: "The last nesting attempt in County Durham, which failed, was in 1998 but there is plenty of habitat in the county for them. It is not as if the county is not suitable and historically they did breed in the county."

And the birds have shown this year that they do have the capacity to expand their range: the Yorkshire Dales chicks were the first in nine years and four reared in Cornwall were the first in 200 years.

However, English Nature says there is no room for complacency given that there were at least 50 birds recorded during the spring and only a very few bred.

Richard Saunders, English Nature's Hen Harrier Recovery Project co-ordinator, said: "This is only the first year of the project so we are not discouraged. We are finding out more about the habits of these birds and what issues continue to threaten their future survival, as well as raising the profile of this magnificent bird of prey with the public. We have been really pleased with the high level of co-operation that we have had from landowners and gamekeepers."

There is a long way to go over the next three years of the project and soon the Geltsdale harriers will leave the site, probably heading towards the coast to over-winter. Next year John Olley and Chris Curtis will be praying that the sky dancers return to breed again. This is a fight for survival which is far from over.