Natural forecasters

It was a glossy autumn morning, polished by a keen east wind. The sun squinted down from the mountain to light up each of the couple of hundred sheep on the dull green of the duach and each new white gable in the growing flocks of bungalows across the bay in Connemara. I felt challenged to start counting them all through binoculars, but gave up and went out to pick an apple, a glossy Jonagold.

And there, perched on the chimney, was the glossiest of birds, a chough, the sun glowing on its vermilion bill and legs and glazing its black feathers with beautiful tones of violet. It was calling sharply, in the ringing tones choughs have, chee-ow! chee-ow!, and kept it up until I returned with my apple, then lifted off and whisked up the hill.

A chough has no business being on its own, perched on somebody's chimney. At this time of year it belongs in a flock, away among the creggans beyond the lake: perhaps 30 or 40 choughs flying rings around the ravens. What should I take from this solitary, declamatory visitation?

Brendan McWilliams, turning his weather-eye on literature, once picked a quote from Macbeth to illustrate the Roman use of auspices, an auspex being literally an avi-spex, an observation of the birds. Here was Macbeth working himself up over the "maggotpies and choughs and rooks" that spoke to one's secret fears - when not, that is, predicting a dire turn in the weather.

If you watch a chough as it takes a drink, advised McWilliams, "it is said to beat the water with its wings if a storm is on the way. If, on the other hand, a chough is heard to caw three times in the hour immediately after dawn, the weather will be good." Was my chimney-chough overdoing the reassurance, or warning me to cash in our Post Office bonds before The Crash?

We have lost the neighbour who knew most about auspices. I think of him when I see the Mhaire fhada, the heron, flying out from the shore to fish the channel on the strand. Herons roosted in summer in the conifers around his farmhouse and their departure to the channel promised, he said, settled weather. He would take the same message from moths in his headlights on the way to the pub at night, or the sound of the curlew, calling twice on its way to the bog. Three calls, repeated twice, however, warned of rain.

His frank interest in nature and level of observation seemed an exception in our community, a glimpse of a cultural currency that finally lost its value with the coming of television. The seaward heron and the code of the curlew were among distinctively Irish contributions to birds-and-weather lore later gathered up by Lisa Shields, as librarian to the Meteorological Service - together, of course, with the infinite subtleties of portent in the fractions and phases of the moon.

Much more awaits attention in the long ranks of ledgers in the UCD Department of Folklore, their myriad pages of popular belief and wisdom collected mostly through Irish. Even a casual browse through Dinneen's Irish- English Dictionary gives a tantalising sense of the connections with nature that have sloughed away from the language's modern use.

Brendan McWilliams recovered some of them, including more about birds and weather, in his meteorological chapter for Nature in Ireland, the scientific and cultural history edited by John Wilson Foster. Rain was promised by a flight of swallows, or a robin hiding behind a bush at morningtime. And, again from the Irish: "When the cuckoo sings on a tree without a leaf, sell your cow and buy bread".

An English meteorologist, Paul Marriott, had the temerity to test birds-and-weather lore against actual performance, in regard to more than 30 species. In his book Red Sky At Night, Shepherd's Delight? (1981) he gave reasonable marks to high-flying swallows as a sign of settled weather (since rising, warm air takes insects up into the sky), but refused, for example, to credit early geese or swans with any forewarning of a bad winter to come. The first arrivals of Brent geese at Strangford Lough and the west Kerry bays - often in August - are an advance guard of non-breeding birds. The main flocks follow by October, and their appearance much earlier may say something about the weather they have left in Arctic Canada but nothing at all of what they can expect from the Irish winter.

Similarly, the size of the autumn flocks of fieldfares and the timing of their arrival in Ireland depends greatly on the abundance of the rowan-berry crop in Scandinavia: when this is good, the birds stay on longer and fewer of them bother to come here. As to the generous Irish berry crop that awaits them this autumn, its abundance was pre-structured in the growth the trees and bushes made in 1997 and has nothing to do with the winter to come.

What about storms, then? The mistle-thrush, the "storm cock" earned wide recognition for singing immediately preceding a high wind. It has certainly been seen uttering wild notes in the teeth of a driving snow-storm, and as an early nester in high branches is clearly a species of some obstinacy.

The "tumbling" of rooks ahead of a storm is another well-attested phenomenon of autumn: a display in which the birds, returning at some height to the rookery, dive sharply down in "a whirling and a vibratory sort of gyration", as one classic account describes. The rooks down the hill have had plenty of chance to show off to me in this way, silhouetted at dusk against an ominous western sky, but I can't say I've ever specifically noticed it.

It would hardly be surprising if birds knew a storm was coming, as pressure falls and the wind stirs. Eels, after all, waiting in November for a dark, wet night on which to migrate from their rivers, feel the earth vibrations - microseisms - that run ahead of depressions and set the water tingling in the last quarter of the moon.