Getting a fix on our noisier owl!

I loved a story from England this summer about the two bird-loving neighbours who, unknown to each other, went out to their gardens at dusk to listen for owls. One of them tried calling up an owl by a fair imitation of its hooting, whereupon the second neighbour responded. The two men kept this up for weeks, until they got talking to each other in the pub . . . It is England's tawny owl which utters the tu-whit-tu-whoo of Georgian poetry. In Ireland, which does not have this bird, it is the male long-eared owl that hoots territorially - hooo-oo-oo - but this so low and soft that only a female long-eared is likely to pay much attention. Their offspring, on the other hand, as hungry fledglings, have voices that carry only too well. About every minute, they make a piercing peeee! like a squeaky gate hinge.

This sound, floating out from an isolated copse of conifers (where the long-eared owls have appropriated the bulky, disused nest of magpies or grey crows) is very much a signifier of what a "screech owl" ought to sound like. And because screech-owl is a popular rural synonym for barn owl, few people actually know that the real barn-owl call (one of a whole repertoire of hissing, purring, screeching and yelling - anything but hooting) is a loud, hissing scream sometimes rendered as shrrreee !

Unsurprisingly, therefore, well over half the birds reported so far to the Barn Owl Survey of Birdwatch Ireland have been long-eared owls - interesting in themselves, indeed, but not the owls ecologists are so concerned about. It's 10 years since the last estimate of barn owl decline - down to 600-900 pairs island-wide, at a very crude estimate - and the present survey, in its third and final season, is showing once again how hard it is to census a bird that is so widespread, yet so nocturnal and elusive.

And the fact is that, outside the breeding season, the barn owl makes little noise at all. Its unsteady, searching flight is the epitome of silence: the big, rounded wings have a felty softness, their edges sculpted to muffle all disturbance of the air. It is the supreme listener of the bird world - even of the owl world - and able to pin-point squeaks and whiffles in the grass well above the human pitch of hearing.

The barn owl is, therefore, more often seen than positively heard: a ghostly, blurred form beyond a car window, as headlights shimmer on its white underparts (this in reports by taxi-men, gardai and ambulance drivers). Flying gulls can catch the light in this way, too, but one good record was from someone whose neighbour had mentioned "a pair of gulls" nesting among straw bales in a shed.

If Ireland's barn owls are, as they seem, much more nocturnal and elusive than their cousins in Britain and continental Europe, it could be due to a difference in prey. One small mammal that mysteriously failed to colonise post-glacial Ireland was the field vole, virtually the staple diet of barn owls further east. It is much more active in daylight than the field and house mice, pygmy shrews and rats that nourish the Irish owls.

The undigested bones and fur of its prey are whooped up by the owl as a tight-packed, rounded pellet the size of a navvy's thumb, and a scatter of these on the ground below a hollow tree or an old building can be good evidence of breeding. A nest in a hollow tree in a housing estate in Gorey, Co Wexford, was watched nightly at dusk by as many as 30 people, who went away pleased - but next winter, wouldn't you know, the local authority chopped the tree down as dangerous.

Loss of hunting habitat has already pushed the barn owl into danger. Its decline in Ireland dates from the 1960s, soon after horses disappeared from farm-work and people stopped growing oats. The switch from hay to silage, the "improvement" of rough meadows with grass that never gets to seed, the rapid removal of grain stubbles in the autumn, the loss of hedgerows - all this has greatly reduced the numbers of rodents and steered them to feed in the last, seed-rich margins of roadside verges.

Hunting them here, the owls are increasingly blinded by headlights and struck by vehicles. Hunting rats around farms, they pick up the latest poisons, designed for "super-rodents".

The different diet of Irish barn owls complicates the prospects for conservation. In Britain and Europe, conserving tussocky grassland automatically increases the supply of voles. Here, the important habitats for study are those in which our owls catch the field (or wood) mouse, Apodemus, and this will need radio-tracking and long watches with night-sight binoculars.

A barn owl has been known to live for 21 years, but the species is not well adapted to growing either wise nor old: most birds that survive their first year can expect another year-and-a-bit if they're lucky. It's to compensate for this high turnover that European barn owls tend to lay a second, or even a third clutch of eggs, and to start breeding young when food is plentiful. But to breed they need a nest near a good hunting-ground. Unlike the long-eared owls, who are somewhat nomadic and use second-hand nests, barn owls like to pick a good hole and stick to it: they pair for life and the female tends to use the nest all year round. The progressive loss of hollow trees and ruins, and replacement of old farm buildings by less accessible ones is forcing the owls to settle for unsafe billets - temporary stacks of hay-bales, for example.

As this year's young owls begin to disperse, Birdwatch Ireland is stepping up its campaign to persuade farmers and other rural landowners to put up nestboxes, either to replace an existing nest site that may be lost, or to provide a new potential home for the owls. There's a special leaflet on the use of 100-litre plastic barrels, tied up out of sight in sheds or trees, which is available from Birdwatch Ireland at Ruttledge House, 8 Longford Place, Monkstown, Co Dublin.

The organiser of the ESB-sponsored Barn Owl Survey (who doesn't care how many times he is told about the same pair of owls) is Dominic Berridge at Rathsillagh, Adamstown, Co Wexford (054-40738 or e-mail: djberrid@iol.ie).