Prodigal nature of ecosystem reflected in Dublin Bay

ANOTHER LIFE:POLISHED by a spring tide and last night's inch of rain, the strand below us mirrors the sky in pale blue – blue and quite bare, but for a thin, black tangle of wrack at the tideline.

Embedded there, could be the odd shattered crab or tattered gull to feed a fox or raven, but, for all its wide reach, this particular White Strand, wave-battered and windswept, is not often one of nature’s takeaways.

Just a few small flocks of tiny sanderlings chase the edge of the tide, searching for miniature, cast-up prey. Ringed plovers, no bigger than a robin, forage for the same scanty little worms and crustaceans.

Walking there, blinking with wind-tears, you’d miss them all till they rise up in alarm.

As winter wears on, however, some of the offshore forest of kelp begins to lose its grip. Swells roll ashore with a cargo of Laminaria tumbling in the surf, all shining, toffee-coloured furls and sudden rude fingers of stems. Piled ashore, the weed conjures kelp-fly eggs and sandhoppers and a lot more shorebirds to eat them: turnstones, dunlin, oystercatchers – even starlings and pied wagtails.

For the great flocks of Arctic waders that sweep down the East Atlantic Flyway in autumn, Ireland’s more constant winter larders are the deep, sheltered bays and city estuaries, their low-tide mudbanks enriched over centuries with organic waste, much of it from people.

In Dublin Bay, spectacular assemblies of a dozen or more different waders and ducks, reflect, as ecologist Roger Goodwillie once put it, “the prodigal nature of the ecosystem”. Just one kind of food, the Hydrobia snails that graze the surface skin of algae on the mudflats, is eaten by the million. Beneath them, burrow teeming amphipods and worms.

Feeding almost shoulder to shoulder sometimes, yet sorted into species and flocks, how do the birds find and share out their prey? This is one topic of Shorebirds of Ireland, (Collins Press, €22.95), an expert, engaging book by Jim Wilson, a former chairman of BirdWatch Ireland.

He leads the reader through the differing makes and sensitivities of bills, from the delicate arcs of curlew and whimbrel, straight spears of egret and godwit, to the orange, cockle-wrenching gear of the oystercatcher (which can live, apparently, to a record 43 years, pushing out new bill as it wears away at the end).

The book is packed with fine photographs. Mark Carmody makes use of long lenses and the special punch of winter light to offer memorable close-up portraits (a golden plover on one leg) and powerful images of birds en masse (the flock of knot, marching away at dusk from a rising tide). Interleaved are big, rich scenes of shorelines in winter.

No book about wildlife can avoid human competition for space on earth and now threats from rapid climate change.

“If any creatures on the planet are going to feel the effects of global warming,” writes Wilson, “shorebirds will.” As the Arctic melts, tundra nesting habitats are changing. Migration to breeding grounds is slipping out of phase with peaks in Arctic insect supply. Already, he reports, at least 38 per cent of Arctic-nesting shorebirds are falling in number.

As for the Irish part of their lives, the alarming estimates of sea-level rise make it hard to see how the birds will cope with the rapid loss of foreshore feeding-grounds and sandbar roosts. Many of these are not only regular seasonal refuges, but age-old, vital stepping-stones between the Arctic and wintering grounds even farther south.

Already, however, climate change is affecting patterns of migration. Since the mid-1980s, seven key species of wader have been shifting their wintering populations on the European mainland. Curlew, grey plover, dunlin and black-tailed godwit are among those reported as moving by more than 50 miles north and east – that is, closer to their summer breeding grounds in Scandinavia and Arctic Russia.

The same sort of movement has been seen in Britain, notably on coastlines without estuaries. It has been predicted that such open-coast waders as ringed plover, sanderling, purple sandpipers and turnstones will all shift away from the west as eastern winters grow milder, and the wetter and windier western coasts threaten small waders with wind-chill.

For Britain and Continental Europe, this contraction of migration may ultimately draw many shorebirds to winter around the Baltic. Most of Ireland’s waders, however, migrate from Greenland and Canada, so their response to climate change is less easy to predict. Jim Wilson, indeed, does not attempt it, but does include a whole chapter on Iceland, the big breeding-ground for many of our winter shorebirds and a stepping-stone for others on their way south.

Perhaps, as Iceland warms and its winter ecosystem responds, fewer will bother to leave Iceland’s shores. We would miss them.

EYE ON NATURE:

Recently we found that moss had been dug up from our back lawn and was lying on top of the grass. After cleaning it up we returned a short time later to find two magpies digging up moss.

Chris Coggins, Stillorgan, Co Dublin.

They were searching for insect larvae.

I photographed a mouse lunching at the bird-feeder hanging from the arch of a trellis in my back garden. It had climbed through a climbing rose and down a thin wire hook to reach the nuts.

Stephen Hunt, Ballina, Co Mayo

It was the delightful wood (or field) mouse, Apodemus sylvaticus. It has larger eyes and ears than the house mouse and longer hind legs and tail.

About an hour out from Roscoff on the ferry to Cork, what seemed like hundreds of dolphins converged on the boat from all directions and stayed for about 15 minutes.

Seamus Hogan, Ballydehob, Co Cork

On a recent walk by Kilcoole Nature Reserve, we noticed a little auk on the water quite close to the shore. There were lots of wigeon and shoveler duck in the Reserve itself. Also sighted were some redshanks, curlews, snipe or woodcock and a few reluctant swallows.

John Dineen, Ranelagh, Dublin 6

Michael Viney welcomes observations at Thallabawn, Carrowniskey PO, Westport, Co Mayo. Email: viney@anu.ie. Include a postal address.