Another Life: On cold, clear mornings - the sort that have airliners chalking the sky with contrails between the mountain and the islands - there's a special shine to the bright red tractor that brings breakfast to my neighbour's ewes, writes Michael Viney.
As he shakes out a long line of beet pulp, they crowd around him - but it's not just sheep that have been watching for the tractor. Within minutes, a flock of common gulls arrives from the little estuary in the strand, hovering above the ewes and dipping to the grass for their leavings. The sun gleams on the gulls' white bellies almost as brightly as it does on the passenger planes heading out to America. The planes drag their sound after them, ventriloquially, but the gulls are entirely silent, which seems to give their flight the extra elegance of mime.
The common gull is in most ways more modest than the bigger, raucous herring gull, and even its name has been thought a mistake, since for long they were the least numerous breeding gulls of these islands. But this must be changing as the herring gull continues its dramatic decline. The 2000 seabird survey found only some 6,000 breeding pairs in Ireland - a drop of 90 per cent in 30 years.
Oscar Merne, who has just retired as head of bird research in the National Parks and Wildlife Service, finds the species "in serious trouble". Writing in Sherkin Comment, the journal published from Matt Murphy's marine station on Sherkin Island, West Cork, he goes out of his way to warn against any repetition of the drastic herring gull culls of the past "unless there is a major justification for it and after non-lethal methods have been tried and found ineffective". In the 1980s, as he reminds us, the bulk of the 20,000-strong breeding population nesting on the privately-owned Lambay Island, off Co Dublin, was wiped out (presumably on government orders, or with official sanction), because the gulls were deemed to be a hazard to aircraft landing and taking off at nearby Dublin Airport.
There's no doubt that the birds had multiplied greatly around the capital in the late 20th century, largely in response to year-round food from trawlers, rubbish tips, and dumping of the city's sewage in Dublin Bay.
Even here in Mayo, in the mid-20th century, an open dump for bacon factory offal supported an inland winter roost of up to 1,500 herring gulls on Lough Mask.
For many people, however, Dublin's thriving population of gulls, peaking in the 1970s, was a welcome part of the capital's character. "In the evening," recalls Colin MacLochlainn (who edits Wings magazine for BirdWatch Ireland), "thousands would head to Sandymount, forming skeins, or formations in v shape, as they headed purposefully towards their roost on Sandymount Strand. You could see them flying overhead every evening. All this was part of the Dublin evening sky, and now that flight to roost has disappeared."
But the official Lambay massacre is only part of the story. The long, hot summer of 1976, as Oscar Merne describes, brought the first dramatic episode of botulism, the bacterial toxin contracted by the gulls when they slash open black plastic bags at rubbish dumps and feed on fermenting tit-bits within. Most infected birds die within 48 hours - in which time thery may well have brought toxic food to their chicks at island colonies. Most of the declines have occurred on the east and south coasts, with their warmer summers. On Saltee Island, off Co Wexford, for example, the 3,000 pairs of herring gulls nesting in the 1970s have fallen to 27 pairs, and former colonies on the Wicklow coast have dwindled to a handful.
Coilin MacLochainn shared his distress at learning of the Lambay Island cull with fellow birders on the Irish Birds Network on the web. But this has brought another perspective on the bird's decline in Dublin, from the eminent ornithologist Paul Milne. As the herring gull population has fallen, so other seabird species have stabilised or increased.
Roseate terns, once brought near extinction by plumage-hunters, have spread from their protected breeding colony on Rockabill, off Co Dublin, (where gulls were also "controlled") to breed on Dalkey Island for the first time.
The manx shearwater has returned to Lambay Island. If the herring gulls on Lambay had continued to increase, so Milne argues, with their predatory designs on chicks and eggs of other species, the puffins would have stopped nesting there.
All this, he says, raises a question that many conservationists shy away from: should predators be controlled when they threaten other species? His own answer would be yes.