Mysterious influx of the hardy white heron

ANOTHER LIFE: The only herons on our shores are the big, old-fashioned, gawky sort, unfurling themselves from the channel to…

ANOTHER LIFE:The only herons on our shores are the big, old-fashioned, gawky sort, unfurling themselves from the channel to fly with contemplative wingbeats, neck tucked back and long legs trailing in the wind - Máire fhada, long Mary, in the local lore, writes Michael Viney.

All down the west, their Irish names are affectionately feminine, from Galway's long Siobhán, to Kerry's long-necked Joany, and Síle and Nora of the bogs. A pity little egrets weren't here in those times to conjure even more inventive folk-names.

They give such pleasure as they spread around the coast: people out walking their dogs can't wait to get home to tell about the first one that they see on an estuary or a suburban stream. But I'm still waiting for the first bird to make it round the mountains and surprise me at sunrise with a gleaming white dot that definitely isn't a gull.

And now another possibility, as the even smaller white Mediterranean heron, the cattle egret, makes its first major assay into Ireland. From December right through January, from Cork to the Shannon, excited reports were trickling in to BirdWatch Ireland - about 80 separate birds at least, judged by the Irish Rare Birds Committee earlier this month.

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Since Ireland's previous records of Bubulcus ibis totted up to 10, this was clearly an influx, a word now almost inseparable from the species. From origins in Africa, cattle egrets have spread to the Americas, Asia and Australasia, with most of their astonishing expansion completed within the 20th century.

This winter's northerly influx has been shared with the Channel Islands and southwest England. A flock of 19 egrets were seen at Cornwall's St Ives and there were more at a score of other places.

It seems like almost a carbon copy of events in the late 1990s that brought the little egret, Egretta garzetta, to the south coasts of England and Ireland. At first, it was an occasional influx, then birds came in winter, with big arrivals in the mid-1990s. Then the first breeding started - in Dorset in 1996 and in Co Cork, alongside tree-nesting grey herons on the Blackwater in the following year.

By 2001, there were 57 nests in three separate colonies on the south coast, and there has been further breeding on the east coast since then. The lovely white headed-plumes in the breeding season are what got Egretta into such trouble in the 1800s - head-hunted, literally, for the decoration of hats.

The cattle egret has breeding plumes too, but of an orangey colour, and at the peak of courtship, the bill and legs turn bright red. But just now, in late winter, watch out for a little white heron with a short yellow bill and feathery jowl, a bit dumpy and hunched when seen with the graceful Egretta.

Lifestyle is mostly what sets the two egrets apart. Egretta is a wetland bird, like our own big grey heron, foraging after frogs, fish and water snails. The cattle egret is a walker rather than a wader, spending long periods on dry land, in the company of large, slow-moving herbivores that kick up grasshoppers and other insects as they move.

Originally, the herbivores were the buffalo of the African savannahs; now they're the water buffalo and cattle of the world, plus anything else (chickens, goats, tractors) that advances at the right speed.

In Africa, the egrets serve their consorts by perching on their backs to peck up burrowing parasites; the hides of Irish cattle will have been chemically proofed.

For a naturally short-distanced migrant, this egret has made incredible leaps - the only bird that made it from the Old World to the New on its own, crossing the Atlantic at the shortest stretch, between the bulge of west Africa and northern South America, then spreading rapidly north into the mid-USA by the 1950s. Given the proximity to Ireland of big colonies in France and Spain, the short hop to Cork is scarcely surprising.

Climate change is the tempting explanation. But what became of the egrets, one wonders, in that week of frosty nights? And what were they finding to eat in winter rye-grass fields, largely emptied of cattle, limited in insects at the best of times and long bereft of grasshoppers?

Cattle egrets, it seems, are quick to improvise. Imported to Hawaii as a free cattle-cleansing service, they bred almost non-stop, chose airports as their favourite flocking grounds and treated the islands' prawn farms as takeaways.

This winter's influx to Ireland may be a one-off, melting away as mysteriously as it came. Or the summer may see some of Munster's black and white cattle with attendant sprites, close about their feet and even on their rumps, but never enough, one fears, to keep foreign midges at bay.