ANOTHER LIFE/Michael Viney: At some point on starry evenings, the dog and I go out to the lawn together, ostensibly for her to pee but really for us both to check on the state of the universe. There we stand, motionless for a while, me with my head thrown back to the sky, Meg with her ears pricked, nose twitching as she monitors the night.
Sometimes, impressed by her attentive silhouette, I am reminded to celebrate one of the great gifts of living where we do. I can enjoy not only darkness, and thus the stars, but also a silence - or, rather, a blessed absence of man-made sounds - that can last for whole hours on end.
True silence in nature is rare and unnerving: one tends to remember it. I stood on a snowy headland in the High Arctic, on a totally still day, contemplating frozen fiords on which nothing whatever seemed to move. The only sounds were the pulses, sighs and gurgles of my own corporeal machine, plus something called, apparently, "thermo-acoustic noise produced by the Brownian motion of air molecules upon the tympanic membrane" - a sort of gentle singing in the ears.
Everything changed when the thaw came and the rattle of water took over.
So what the dog and I now share on the lawn are sounds scarcely changed in the 10,000 years since the ice melted: running streams, a breeze in the trees, the ceaseless heavy breathing of the ocean. Plus, in Meg's case I suppose, the odd hedgehog, rat or fox, or the sneaky, post-glacial cat from the farm next door.
I take for granted that she can hear more than I, with her big ears, her special sensitivity to high-frequency squeaks and rustles. Most of auditory wildlife, one is tempted to assume, is better at hearing than we are, since safety and food supply so often depend upon it. Owls, for example, can pick up the merest twitch of a mouse in the grass and swoop in pitch-dark to nail it: doesn't that prove their superior hearing? When it comes to absolute sensitivity to sound, nocturnal owls are far ahead of most daytime birds, but their lowest auditory threshold is actually no keener than that of people or many other higher mammals. As for vision, the retinas in both the owl's eyes and our own are near the theoretical limit of sensitivity. And while the owl's pupils, like the cat's, are designed to give brighter images in low light levels than our own eyes provide, we are by no means as bad at seeing in the dark as most of us seem to think.
Anyone who lives outside the range of street-lights knows the almost infinite range of "darkness". Depending on the state of the moon, degree of cloud cover, time of year, the illumination of night-time can vary enormously: 10-million-fold, at one estimate, even in the same locality. A few minutes acclimatisation, and the pupil widens like a camera iris to gather as much light as it can.
Our forebears, reared by candles, oil-lamps, single 60-watt bulbs, undoubtedly developed and retained more "night-sight" than most of us possess today. Just as the hearing of millions of people has been blunted by over-amplified music, human visual acuity must have been lost in the barrage of light that millions now find indispensable both inside and outside the home.
Insulated from the natural world and generating ever-more-extreme levels of sound and light, even our senses become culturally and technologically conditioned and diminished.
The ability of barn owls and long-eared owls - our two resident woodland species - to locate and capture prey in total darkness by auditory cues alone has sometimes suggested an extra sense, like the echolocating radar of bats. But their phenomenal accuracy is honed by a special sensitivity to certain frequencies of sound, and by complex, asymmetrical ears that help them pin-point the source of it. Those of the long-eared owl are not, in fact, the cat-like tufts on its head (the function of which is still uncertain), but long slits in the feathers at the side of its head.
Both owls and humans are probably equally good at judging the direction a sound has come from: we both swivel our heads to bring binocular vision and hearing to bear. The typical facial ruff of an owl concentrates sound to the ears like a parabolic dish, so that a barn owl, for example, can refine the location of a mouse to within one degree. But actually flying blind to seize a mouse in pitch-darkness may also need the confidence and extra cues that come with knowing a place "blindfold": a feat best reserved for home territory.
FOR humans, finding owls presents its own challenges. Outside of the breeding season the barn owl makes little noise at all, and its big, rounded wings have a softness shaped to muffle all disturbance of the air. But at least it is white underneath and catches headlights - sometimes all too literally, as, suddenly blinded in its hunt along road verges, it is struck and killed.
The barn owl is in well-publicised decline, hastened by a loss of nesting-holes in hollow trees, ruins and old farm buildings and a susceptibility to modern rat poisons. The long-eared owl has advantages in nesting behaviour that help to make it much the commoner of the two - but it is still one of the least observed of all Irish birds, especially in winter..
Relaxed and close up, the long-eared presents itself as a round-headed owl with big eyes and what has been praised as "an inquisitive and friendly disposition". But it spends its days aloft, frozen into a cryptic pose close to the trunk of a conifer tree and pretending to be part of it. It stretches upwards to make itself thin, holds a wing in front of its body, and narrows its bright orange eyes to slits. Its long ear-tufts stick up like little twigs and the camouflaging patterns of its plumage complete the vanishing act.
Were it not for its noisy young in spring, the exact whereabouts of long-eared owls would be even more obscure, since the territorial hoot of the male - hoo-oo-oo - already under way in some areas, is so low and soft that only a female long-eared is likely to pay much attention. The young owls, on the other hand, have voices that carry only too well. As fledglings, they follow their parents through the crowns of the trees, crying a non-stop pee-ee! like the squeak of a rusty gate.
If they can survive the toxic hazards of their autumn onslaught on rats (three-quarters of their food is field-mice), the long-eared owls would seem to have one great advantage over barn owls. They nest happily on the fringe of moorland conifer plantations, often in the disused nests of magpies and hooded crows. In this, at least, they must find themselves well provided for.
•Michael Viney welcomes observations sent to him at Thallabawn, Carrowniskey PO, Westport, Co Mayo. E-mail: viney@anu.ie Observations sent by e-mail should be accompanied by a postal address