Tern population continuing ‘to soar’ in Ireland

There are five species of tern here, while Rockabill Island represent 80% of the roseate tern’s European numbers. It’s a conservation success story, says Dan MacCarthy

Tern population continuing ‘to soar’ in Ireland

NATURE never fails to surprise, nay stagger. A colony of terns off Dalkey Island in Dublin doesn’t look massively adventurous as they sweep, starling-like, above the pier and over to the craggy outcrop off Dalkey Island known as Maiden Rock. But it is.

Neither does the magnificent Manx shearwater look docile — a frequent visitor to the area, in addition to the terns. But that bird, too, is hugely adventurous, says Niall Hatch, development officer with Birdwatch Ireland. The Manx shearwater is known to fly to the Bay of Biscay, and back, in a day in search of food.

A group of 30 birdwatchers is assembled at Colliemore Harbour, Dalkey, Co Dublin, in front of an array of sophisticated telescopes, most aimed at Maiden Rock and, next door, Lamb Island, and fewer at Dalkey. The South County Dublin branch of Birdwatch Ireland has organised this watch for the tern nesting season.

The tern project has been ongoing for 20 years. It was 10 years before any roseate terns took up residence. Most of the roseate terns that have passed through here would have come from Rockabill Island, where they have become habituated to nest boxes, says Niall.

“So, we thought they would nest here, if they did so on Rockabill, and it worked. It took ten years, but it did work. And it’s great when something like that comes to fruition,” he says.

BirdWatch Ireland is responsible for the protection, management, and monitoring of the birds at five, key, east-coast colonies, of which Maiden Rock, at Dalkey Island, is one. They are an Irish conservation success story, says Niall.

Three species of tern breed at Maiden Rock — the common tern, the Arctic tern and the roseate tern. The roseate tern is the focus of the conservation project — the species that uses the nest boxes. The other terns don’t nest in the nest boxes, they nest beside them.

“We put out gravel at the start of each season. They are all just summer visitors. The common terns and the roseate terns go to the coast of west Africa; the Arctic tern goes all the way to the Antarctic. It has the distinction of travelling further than any other bird, in its life,” says Niall.

The roseate tern is restricted in number and Ireland is home to 80% of the European population, and the largest Irish colony is on Rockabill, off the coast of Skerries in Co Dublin.

There are two other breeding species in Ireland — the sandwich tern (largest), and the little tern (main colonies in Kilcoole, Co Wicklow and Baltray, Co Louth). In the grand scheme of things, the number of roseate terns that nest in Dalkey is quite small, but it is still one of the most important colonies in Europe, as evidenced by the presence of birdwatchers from Switzerland and Hungary.

“We have had a maximum of 11 pairs of roseate terns nesting here and, this year, just one — but that’s the way it goes. The terns usually arrive in May. They fly up and down the coast for the first few weeks and then they start to nest after a courtship display,” says Niall.

This year’s Rockabill Island project is very successful, with 1,250 pairs nesting — 80% of the European population. The project at Maiden Rock is carried out in conjunction with Dun Laoghaire/ Rathdown County Council. The islands are under their control. Dr Stephen Newton, who is head of seabird conservation at Birdwatch Ireland, oversees the project.

“We make a couple of visits in the summer. The little chicks have rings put on their legs to make sure they are developing correctly. Maiden Rock is off limits to everyone else,” says Niall.

Dalkey Island, and the adjacent Lamb Island, have a rat population that could be a devastating threat to Maiden Rock’s terns, but they are kept away by a strong tidal current and dearth of vegetation on the rock. There is a concern mink could reach the island, so the group is on the watch for that eventuality.

Other predators of terns include gulls, but there is safety in numbers and the tern colony is able to drive them off. As we talk, an Arctic tern swoops low, on the lookout for sand eels and sprats. Although they are sea birds and spend all of their lives on the ocean, they can’t swim. They dive in and come straight back out. “If they stay in the water for more than a few seconds, their feathers would become waterlogged and they would drown,” says Niall.

During their lives, the Arctic terns travel the equivalent of from here to the moon, and back. Birds tracked in Holland, then Dalkey and Sandymount Strand, had flown to Cape Town, in South Africa, turned into the Indian Ocean, taking in Madagascar and the Seychelles, over to New Zealand and then Antarctica, and then back. “What a privilege it is to have birds like that here. Ireland is far and away the easiest place in Europe, if not the world, to see the species. In late August and September, you’re guaranteed to see the roseate terns in Dalkey,” says Niall. And just to show that the future is bright — for the watchers, as well as for the birds — Niall says there is a growing youthful interest in the terns, excited by seeing the young chicks in their nests or the parents stuffing a fish into their mouths.

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