Blow-ins breed along the Blackwater

Somewhere "in southern Ireland" (in fact, on a leafy stretch of the River Blackwater valley, which still doesn't tell you more than you need to know), a dozen twiggy platforms built in a long row of beech trees confirm that Ireland now has a new species of native heron. Egretta garzetta, with nuptial plumes so elegant that they once threatened its very survival, has finally expanded from Europe to settle as an Irish breeding bird.

The little egret is spread across the world from Europe to Japan, from Australia to Africa. Like America's snowy egret, which has even more impressive headplumes in the breeding season, it was quite wiped out in some places by the demands of the highsociety hat trade, a market that ceased only with the first World War. But the egret family has also undergone some extraordinary expansions, and Egretta garzetta seems to be launched on another of them. The spreading of its range north and west in Europe has been one of the most spectacular waterfowl trends of the 1990s.

It began visiting Ireland more than 40 years ago, a startling white stranger on muddy creeks and estuaries, particularly in the south. Then, in the 1970s, the birds began coming in numbers and staying for longer, and by the mid1980s, more and more of them were both summering and wintering here. A comparable build-up in the south coast of Britain produced the first breeding birds, so that nesting seemed imminent in Ireland as well.

What was remarkable, when it finally happened last spring, was that it involved so many pairs of birds. The egrets' first breeding season is described in the 1997 issue of Irish Birds (just published by BirdWatch Ireland), by Patrick Smiddy, a Cork naturalist, and Brian Duffy of UCC's Department of Zoology.

It was late last April that they found the first two pairs nesting in a heronry in woodland on the Blackwater and eventually there were a dozen nests, all built of sticks. Some were flimsy platforms but others were large and solid and may have been old herons' nests that survived the winter.

The eggs were laid between April 20th and May 10th, which matches the dates when most eggs are laid in, for example, the marshland of the Camargue, in southern France. The chicks survived in all but one of the nests. There were 29 of them, fed with regurgitated food, and they soon led a vigorous life, walking around on the branches at a fortnight old and beating their wings to strengthen them. At a month old they could fly but were still begging their parents for food.

As this column is written, the scene at the heronry is a repeat of last year: the first powder-puff chick should be hatched by today. The sheltered, balmy microclimate of the Blackwater valley, with its riverbank woodland, made it a natural bridgehead for the egrets but their spread to other heronries could be surprisingly rapid. Most coastal counties have had records of the birds, often of several birds together.

Their present expansion is a reminder of the astonishing spread of the cattle egrets, once confined to the Mediterranean and Africa and other decidedly southern latitudes in the Old World. Around 1915 a few appeared in British Guiana in South America, having perhaps been blown across from Africa's "bulge". Within 20 years, the egrets (which seem to have a special affinity for cows) numbered thousands and had spread across to Colombia. Today, there are cattle egrets as far north as Newfoundland, with nesting common all along the Atlantic coast, from Maine south.

So, little egrets at Thallabawn are probably only a matter of time: the lagoons and reedy marsh behind the shore are made for them. But another paper in Irish Birds reminds me of the summer, a decade or so ago, when a trio of even more extraordinary visitors was reflected in the lake. The flamingoes looked very much at home, I must say, trailing their beaks in the shallows, but the deep coral pink of their long necks marked them as Chilean exotics, escaped from a zoo or some private collection, rather than as southern Europe's much paler greater flamingoes, wandering up from the Camargue.

The discussion in Irish Birds, by Jim Fitzharris on behalf of the Irish Rare Birds Committee, is about the flamingoes which were exciting birdwatchers in eight Irish counties in 1995 and 1996, from Armagh and Derry down to Clare and Kerry. They were greater flamingoes, all right, but were they genuine vagrants or escapees - and was there ever really more than one?

At the time, belief in a small influx of wild birds from the south was quite widespread. However, sifting the records, the Rare Birds Committee found a complete lack of overlap in dates: just one bird could have inspired them all. As to its origin, the pros and cons weighed up by the committee are a model of ornithological jurisprudence.

They even put out word on the Internet: had anyone in France or Spain seen flamingoes where they shouldn't be? No, but there are some 200 to 300 captive greater flamingoes in Britain alone, and probably many without rings or with wings unclipped. "After careful deliberation" the Committee returned an open verdict.

As the activities of BirdWatch Ireland enthuse more and more young people to take up binoculars and telescopes, the sheer increase in observation-hours means that more and more rare birds are actually being sighted - and more and more hopeful reports are - actually quite wrong. When Pat Smiddy was still secretary of the Irish Rare Birds Committee, he noted that the number of observers who can't be bothered to submit field notes to back up their reports has reached "alarming dimensions".

The new Irish Birds gives a feeling both for the extraordinary rate at which "rare" birds are making their debut and for the sort of evidence a record needs to be accepted. The pine bunting, which drew more than 500 birders to the Wexford Wildfowl Reserve in 1995 and the Terek sandpiper which turned up in the county in 1996 are subjects of delightful paintings by David Daly, who saw both "species new to Ireland" for long enough to make sketches and notes.

Irish Birds 1997 is available from BirdWatch Ireland, Ruttledge House, 8 Longford Place, Monkstown, Co Dublin, at £10 including postage.