The sun should always be at this angle, raking the hillside for every rock and hollow, laser-lighting every ewe, combing the rushes for spider-webs. Only in November, with the first bite of frost, do you get this revelation of texture and detail, as if the landscape had been properly brought into focus.
Down on the duach, where the light sorts even close-bitten grass into individual blades, the choughs are suddenly walking on lacquered vermilion legs, prodding under sheep-dung with nail-varnished bills. At the lakes, each whooper swan floats on its reflection in a gleam of whiteness quite as intense as the silvcr specks of airliners unzipping the westward sky.
The day's stillness amplifies the whoopers' calls, their sociable descant glancing off the water, fluting off the cliff: a ready-made track for one of those CDs of Sounds to Meditate By. Crouched near the cliff's edge, between the swans and the sun, I merge with a lichen-stubbled boulder, but the restless flick of the dog's tail is too much, as usual, for the lake's jittery ducks. Mallard and widgeon take off like rockets, one salvo after another, their circling flights subsiding only slowly, as ripples do; as if I had thrown a big rock into the lake.
Duck lose no time in falling into formation. That tight chevron spins the vortex of air from each flapping wing into an upwash for the bird behind, thus saving on group energy and heartbeats (so we were told recently in Nature). Whoopers seem to prefer to fly in half a chevron, a slanting line astern, which must have a similar benefit. This is how they arrive at the lake in autumn, hugging the shore in twos and threes and half-dozens. There are few things more stirring than to be overtaken by a low-flying line of swans, their bodies rocking in a gentle ripple that travels from beak to tail.
Most of Ireland's winter whoopers start out from breeding grounds in the north-east of Iceland, where iron in the lake muds can stain their neck-feathers for months. A long-term ringing programme has traced their movements to Ireland and Britain, and one swan (tagged with the leg-ring CPA) was fitted with a radio-transmitter in 1995 and tracked by satellite. Disconcerted by such attention, it hung about on its lake until early November, long after most of its fellows had flown, and then headed south-east on a non-stop, 36-hour flight from Iceland to Donegal Bay, Co Sligo and then to a lake near Knock, Co Mayo.
Most of the whoopers migrating to Ireland make their first landfall around Malin Head. Some swing east and arrive at Lough Foyle, others veer west to Lough Swilly. Many stay there for the winter, but thousands move on rapidly after the first, excited assembly.
There's a busy route to Scotland and another down to Lough Neagh and Lough Erne, each of which can host 1,200 swans or so. From here, many split up into smaller groups and fly off to the shallower lakes and turloughs of the midlands and west. In the Shannon floodlands, a flock of 60 overhead can seem to fill the sky, and sometimes, as in the big flood of 1992, a couple of hundred may herd together on the highest meadows.
Here at Thallabawn, this autumn's gathering of 60-odd swans seems plenty - indeed, more than we're used to. That fits with the census of Ireland's wintering whoopers carried out last January, which recorded the highest-ever total on the island. At 12,730, it reflected the increase in the Icelandic flyway whooper population, up by a third since 1995. Mild winters and extra grass are good for swans as well as cattle.
Counting such restless and mobile birds needed specially co-operative effort, professional and voluntary, to cover more than 1,000 sites without logging the same swans twice. The organising team was drawn from, among others, BirdWatch Ireland, D·chas and the Irish Whooper Swan Study Group, and their report is published in the new issue of Irish Birds, the annual journal of BWI.
The census also counted Ireland's third kind of swan, still known as the Russian goose to many along the Shannon callows, a reference both to its breeding grounds in eastern Europe and its dainty, goose-like demeanour.
A century ago, Cygnus columbianus bewickii, or Bewick's swan, was Ireland's most numerous wintering swan, hugely outnumbering the whooper. On Mayo's Mullet peninsula, in the severe winter of 1892, upwards of 1,000 Bewicks spent weeks on the lakes at Cross and Termoncarragh. Today, this swan is on an upswing on its wintering grounds in north-west Europe, increasing over the past 30 years from about 7,000 to 30,000 - but far fewer are reaching Ireland. The count last year found only 382. The reason may be partly milder winters, partly the free barley offered at major UK wildfowl sanctuaries.
Irish Birds costs £11.81 from BirdWatch Ireland, 8 Longford Place, Monkstown, Dublin.
The Irish Whooper Swan Study Group welcomes news of tagged birds to 100 Strangford Road, Downpatrick, Co Down, BT 30 7JD.
