Irish scientists unbox simple way of conserving roseate tern seabirds

24 Aug 2022

A roseate tern emerging from a wooden nesting box. Image: Brian Burke

A tiny island off the coast of Dublin is home to 85pc of Europe’s roseate terns. The species is now flying thanks to the nesting boxes put out for them by researchers.

Scientists from University College Dublin (UCD), Trinity College Dublin (TCD) and Birdwatch Ireland have confirmed that a simple method of conserving a seabird species is proving effective.

For the past three decades, Birdwatch Ireland has been putting hundreds of wooden nesting boxes out for roseate terns in the hope that they will provide a safe place for them to shelter. The group is hoping that its simple method will help conserve Ireland’s population of the birds.

Around 85pc of the total population of Europe’s roseate terns live on Rockabill, a tiny land mass off the coast of Skerries in Co Dublin. The island is only around the size of a football pitch.

The success of the boxing method is thanks to the fact that roseate terns are different from other seabirds in their nesting habits. Like most seabirds, they nest on the ground. Where they differ is they like to lay their eggs in sheltered places rather than open areas.

They often choose vegetation beside rocks as nesting places and they like to hide their eggs from dangers such as predators and bad weather. Due to Rockabill’s small size, it can be hard for the birds to find appropriate places to raise their young.

However, a new report that analysed data on roseate terns on Rockabill island revealed that there has been a great resurgence in the population of breeding pairs, and that these birds have gone on to boost other roseate terns colonies in Wexford and the UK.

When scientists compared the difference between their boxing strategy and the traditional method of leaving the birds to figure it out for themselves, they discovered that the boxes had indeed helped the birds. More eggs hatched and more chicks survived when they were in the boxes. In some cases, local school children decorated the nest boxes before they were deployed to the island as a way of learning about conservation.

The study was published in the journal Ecological Solutions and Evidence.

Dr Darren O’Connell, a co-author of the article, conducted the data analyses during his PhD in TCD’s School of Natural Sciences.

“It is fantastic to have found that over three decades of a hard manual slog by Birdwatch Ireland wardens – during which time they put out hundreds of nest boxes on the island each year – was more than worth it. What seems like a simple conservation strategy is proving to be very effective by having a really positive impact on roseate tern breeding,” he said.

“These sorts of follow-up analyses are really important as they look into how successful any conservation actions have been and let scientists know whether they are putting effort into the right areas,” added O’Connell , who is now a research fellow at UCD.

Brian Burke, scientific officer with Birdwatch Ireland and also a co-author of the study, was a Rockabill warden for three years. “It’s great to now have the science to back up what we’ve been doing, and hopefully other conservation projects can learn from this,” he said.

“Rockabill is an amazing place and we’re extremely lucky to have such an internationally important seabird colony on the doorstep of our capital city. The tern warden job is a tough but rewarding one as nothing beats the sight of the fledgling terns all across the island in late summer. When you see them thriving you know all that hard work has been worthwhile.”

The conservation project is funded by the National Parks and Wildlife Service of the Department of Housing, Local Government and Heritage.

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Blathnaid O’Dea was a Careers reporter at Silicon Republic until 2024.