Study: Nest boxes boost Roseate Tern numbers

For years, conservationists working to protect endangered Roseate Terns have provided nest boxes for the birds on their breeding islands in Ireland, the northeastern US and eastern Canada. A new study published this week by the British Ecological Society shows that boxes make a big difference to the birds’ breeding success.

However, that is not always clear. In a 2020 summary from Birds of the Worldthe authors noted that “Roseate Terns readily use these artificial sites and in some colonies appear to prefer them over all natural sites. Although artificial These nests probably allow more pairs to nest in some colonies than would be possible without them, this has not been shown in a controlled study and it is not clear whether they increase breeding success or simply accept the pairs that would have been successful in breeding. in natural areas.”

Today, conservationists and scientists from BirdWatch Ireland, Trinity College Dublin, and University College Dublin say nest boxes are contributing significantly to the success of Roseate Terns on Rockabill Island, off the coast of Dublin.

Ireland is home to most of Europe’s Roseate Terns, and the small Rockabill, about the size of a soccer pitch (1.5 to 2 hectares), hosts 85% of Europe’s population. The number of breeding pairs is now 10 times what it was when the project began in 1989, and the chicks that hatched and started at Rockabill have gone on to strengthen other important colonies in Wexford and England.

And every year for the past 33 years, BirdWatch Ireland conservation wardens have placed hundreds of wooden nest boxes on Rockabill Island, effectively giving the terns a safe little nesting house.

Roseate Tern numbers have increased, but risks remain

Like most seabirds, Roseate Terns nest on the ground, but where most tern species prefer open areas to lay their eggs, Roseate Terns nest in sheltered areas – usually under plants or next to rocky overhangs or in crevices. They like their nests hidden from above and from a distance to protect them from predators and bad weather.

Scientists had hoped that nest boxes would provide additional shelter, but by analyzing 15 years of data comparing the impact of traditional open nests to nests in nest boxes, they found that their approach was having a greater positive effect.

Their tests show that the nest boxes helped the Roseate Terns have more success raising their young: More eggs hatched, and more chicks survived to fledge as young ones. born in nest boxes.

This suggests that the nest boxes help protect the terns from bad weather, predators, and even from conflicts with their neighbors, while also making the best use of the limited space on this small island in by allowing for a higher density of nests.

“It’s amazing to know that more than three decades of an arduous manual slog by BirdWatch Ireland wardens – during which time they remove hundreds of nest boxes from the island every year – has been more than worth it,” said Darren O ‘Connell, a co-author of the article and a Research Fellow at University College Dublin. “What seems like a simple conservation strategy is proving to be very effective by having a really positive effect on Roseate Tern breeding.”

Co-author Brian Burke, Scientific Officer at BirdWatch Ireland, added: “It’s great that there is now science to back up what we’re doing, and hopefully other conservation projects can learn from this.”

The nest boxes distributed by the wardens are cheap and easy to make, and on another positive note, many have been made and colorfully decorated by students at the local Balbriggan Community College, helping to open eyes to the importance of preserving our precious biodiversity.

Thanks to Trinity College Dublin for providing this news.

Watch a video about Roseate Terns using nest boxes in Ireland