When it comes to birds, one good tern deserves another

ANOTHER LIFE:YEARS AGO, BEFORE the rooks were evicted from the sycamores down the hill, they would fly up to raid my potatoes in the dawns of early autumn. The gleam of pale tubers exposed by rain alerted the birds to the harvest in the ridges, where they dug and pecked assiduously, leaving great stab wounds in many of our best Records. They would also fly off with lesser spuds (po-eens, in the country term) wedged in their beaks. Oval and ivory-coloured, they looked, now that I think of it, rather like eggs.

This is prompted by a photograph thoughtfully e-mailed by the naturalist Éamon de Buitléar. It showed the information billboard on offer to passing walkers at Kilcoole on the Co Wicklow coast, where a trio of BirdWatch Ireland wardens have been guarding Ireland’s biggest colony of rare little terns, nesting along about 400m of the Murrough shingle bank.

By July 9th, as the chalked figures showed, 95 pairs of terns had made 129 nesting attempts, producing 54 chicks and 67 fledglings, with 51 eggs left to hatch. Among the losses, 18 nests were abandoned as infertile, six were swept away by a high tide and eggs of 16 nests were taken by a single rook.

The blog by the wardens had more to say about “Rupert”, assessed as “a rogue nonbreeder” among rooks, which snatched no fewer than 35 eggs, “a serious blow to the colony”. He appears to have picked his moments, making his raids in midweek periods of poor weather, when few walkers were about, or at times when the warden was busy at the other end of the colony. “In the time it took me to run the 200m to where the rook had landed,” noted the day warden Niall Keogh, “it had already munched 3 nests!”

Rogue rooks must rank as a little unusual among the many potential predators on the little tern’s brown-flecked eggs: nocturnal hedgehogs, foxes, rats, stoats and badgers all share an appetite for them, to say nothing of hooded crows, or the peregrine falcon that took three adults from the colony this summer and a great black-backed gull that swallowed another one whole. Defences have included netting and electric fencing, a series of lamps and flashing lights, a night fire on the beach and a spotlight wielded by the night warden, Cole Macey. With a third colleague, Jason McGuirk, the birds have been guarded around the clock since early May.

The little tern, Sterna albifrons, is the rarest and smallest of Ireland’s five breeding tern species – two-thirds the size of the common tern, for example – and its black mask and long and pointed bill give it a bantam defiance. But the male sweetly offers fish to tempt a mate in courtship, and the fast and fluttering aerobatics of the pair are especially delicate and graceful.

I have watched the terns prospecting our own strand, but the nearest summer colony, one of half a dozen small gatherings around the Irish coast, is farther north in Mayo, at the Mullet Peninsula. Globally, its distribution is enormous, ranging even far up American rivers , but the bird chooses every nesting site carefully, with the right camouflaging pebbles among which to lay its two or three eggs.

Along with natural predators, the unwitting tread of human walkers and the gleeful rush of their dogs, tide and weather can take a heavy toll on nests in a single night. Since protection at Kilcoole’s Murrough shingle bank began in the 1980s, the BirdWatch wardens have perfected moving nests out of danger when an easterly gale or spring tide threatens those too near the tideline. This means re-creating the hollowed scrape and its surroundings, with particular big stones and bright pebbles reinstated exactly as they were, a metre or two up the shore, and then transferring the eggs. The operation, if successfully accepted, may need doing all over again the following day.

When the chicks are about three days old, the parents move them down the shore to hide among the debris at the tideline while waiting to be brought their food. By this weekend most of them are fledged or flying, and the mass alarm into the air provoked by passing peregrines gives the wardens an ideal chance to do yet another population count. Their work goes on until next month, when the terns move off before their ultimate migration to west Africa.

Their public information board has been remarkable, not least for its list of “other wildlife” seen at or from the Murrough. Among 114 species of bird are many any twitcher would welcome to a life list: osprey, hobby, quail, marsh harrier, Balearic shearwater, short-toed lark . . . That just shows what you might spot passing when perhaps you should have been watching for the approach of Rupert, the rook.

Eye on nature

While walking on Sandymount Strand I discovered a creature emerging from the sand. It was oval, six and a half inches long, with many legs and a rainbow-coloured rim along its perimeter. I returned it to the sea, whereupon it dug back into the sand.

Pauline O’Reilly, Sandycove, Co Dublin

From the photograph you enclose, it was a sea mouse, a marine scale worm that lives on soft substrate in shallow and deeper water. As its name suggests, it resembles a mouse.

During summertime over the past two years we have had a bird fly in circles around our house during the evening and sometimes late into the night. Then it climbs and swoops downwards, when it makes a warbling throaty noise.

David Callaghan, Glandore, Cork

It is snipe drumming. The sound is made by the air rushing through the tail feathers.

In a barn behind our house, martins, starlings and bats live in apparent harmony. In early July the martins started flocking in large numbers, perching on a nearby roof and on electric wires. This usually happens later in the summer.

Alec Somerville, Laghey, Co Donegal

House martins normally leave during August and September. It seems early for gathering, but swallows were seen leaving early this year too.

Michael Viney welcomes observations at Thallabawn, Carrowniskey PO, Westport, Co Mayo, or e-mail viney@anu.ie. Please include a postal address