Busy roads, barn conversions, golf courses have all but done for the farmer's friend. Now the hunt is on for Old Hushwing

Tracking down Old Hushwing was not going to be easy, especially among the manicured golf courses and exclusive housing developments of the stockbroker belt.

"I don't think we are going to be lucky here," said Monica Johnson, striding across a field towards a line of willow trees sheltering a stagnant brook. "It's almost the right habitat - fairly long, tussocky grass near to woods - but it's too built up all around and there are no derelict buildings, no barns."

A member of the Hawk and Owl Trust, Monica was initiating me in the ways of the barn owl, traditionally known as the farmer's friend for its success in keeping down rodents. So valued were the birds that farmers used to build owl holes in their barn gables to allow them easy access.

However, the barn owl is in such steep decline it has been declared a threatened species and a major effort is under way to save it. Fewer than 4,000 pairs remain in Britain, and here in Surrey, where Monica was training me as a Project Barn Owl volunteer, there are 34 pairs at most, making it one of the worst-hit regions.

Project Barn Owl - a three-year-survey run by the Hawk and Owl Trust with the British Trust for Ornithology, and designed to provide the most accurate total yet of the British barn owl population - is nearing the end of its first year.

According to Humphrey Crick from the BTO, early reports from volunteers are positive, showing that new barn owl nest boxes have been spotted in a large number of the 1,100 4km sq slabs of land that are being monitored. However, Mr Crick and others striving to save this beautiful bird will not be able to predict its fate until the spring.

Knowing the owl's susceptibility to cold and wet weather (Britain is its most northerly European outpost), conservationists are aware the approaching winter could be crucial to the survival of the species here.

As Monica peered up into the branches of a rough, sturdy oak, she explained that the volunteers are trained to espy possible nest sites by searching for the tell-tale signs of white, paint-like stripes left by droppings and the presence of regurgitated food pellets. If lucky, she said craning her neck to get a better view up the oak's trunk, the volunteer might catch a glimpse of Old Hushwing swooping silently across a field at dusk on its wide, soft-feathered wings, or hear its distinctive cry.

It does not hoot like its tawny cousin, but makes a high-pitched rasping shriek which has earned it its other nickname, the "screech owl".

Observations provided by the volunteers will give conservationists essential information on which to base annual monitoring and a 10-yearly survey, and predict what effects future changes to the rural landscape will have on the bird. In short, they will have a pretty good idea of how close to extinction the barn owl is in Britain and how to save it.

Fears for the future of this magnificent bird of the night are justified, now so much of its countryside habitat has been destroyed. Project Barn Owl was set up in response to frightening statistics thrown up by a survey 10 years ago which found that Britain's barn owl population had plummeted by 70 per cent since the 1930s.

The four counties that suffered most were North Yorkshire (which lost 89 per cent), Leicestershire and Rutland (90 per cent), Middlesex (93 per cent) and Hertfordshire where the population fell from 210 pairs in 1932 to just 10 in 1985 - a 95 per cent drop.

Changes in farming practice, especially the destruction of rough grassland and hedgerows (home to numerous small mammals which make up the majority of the barn owl's diet), and increasing traffic and road-building were mainly to blame. In the 50 years to 1985, as many as 5,000 barn owls were killed on the roads each year and a number also died of poisoning from agricultural rodenticides.

More recently, the drive to convert barns and other farm outbuildings into studios, garages or rural hideaways for city folk has meant many birds being turfed out of their homes.

Barn owls will inhabit holes in dead trees and nest boxes and have been found nesting in quarries, dams and bridges, even a windmill, but they are fussy about their homes and really only like barns. Ideally, says the BTO, barns should not be converted, but if they are, then the least owners should do is put up a nest box near by to give the owls alternative accommodation.

Another cause of their decline has been the severe winters and the increase in snow cover that Britain has experienced during the last 50 years.

In our patch of Surrey, Monica made plain, we were not going to be able to improve the statistics. Clumps of densely packed houses covered most of the study area, separated by young healthy trees, without a nest hole in sight. Patches of open space had been given over to intensive market gardening and golf courses with close-cropped fairways.

"Everybody's obsessed with neatness," said Monica as we neared a dead tree she had spotted earlier. "Here in Surrey everything is so tidy. What's wrong with wild, scruffy areas? They are essential for all sorts of wildlife, especially barn owls."

The tree stood next to the deserted 10th fairway on a municipal golf course, in the shadow of a humming electricity pylon. Its skeletal branches twisted skyward above the green canopy of horse chestnut around it.

We crept up to its trunk, picking our way between fallen branches. The copse was silent and still. The late-summer sunlight trickled through the leaves. There was a hole, two holes. And odd dark stains on the bark. We ran through our checklist. There were good hunting grounds near by, in an unkempt meadow lying to the south, no doubt harbouring a wealth of voles and mice. No barns around, but this tree was perfect with its inviting holes. Surely this was our quarry's lair.

"No," said Monica after a brief examination of the holes.

"There are no droppings, no white stripes. It might be home to a tawny, but not a barn owl."

This had been our last chance to find Old Hushwing in this corner of Britain and we had failed. In an area that might once have been a healthy mixture of scrub and farmland and which would quite probably have housed several pairs of barn owls, there was now not one.

Valuable as our negative report would be to Project Barn Owl, it was none the less disappointing to confirm conservationists' fears that this majestic bird is, indeed, in serious trouble.