Cork’s barn owls on the rise thanks to nest boxes

By Peter McCarthy, Corkman

They have one ear higher than the other, can turn their heads through 270 degrees, their hungry young make a sound between snoring and hissing, and the blood-curding night-time cry of the adults may have inspired the legend of the banshee. But you probably know this iconic bird best from the opening titles of “The Late Late Show.”

The barn owl, one of Ireland’s native birds of prey, is an elusive nocturnal hunter, scouring verges and hedgerows for the rodents they survive on. And like many of the country’s other raptors, they’re on the Red List of high conservation concern. Rodenticide and road kills have whittled away their numbers but the greatest threat they face is loss of habitat as farming becomes ever more intensive.

However, there are grounds for hope. In Cork, barn owl numbers are slowly recovering, with nest boxes built by volunteers playing an important role. The plywood boxes are installed high up near the roof inside the galvanised farm sheds that have largely replaced traditional barns, in derelict buildings, and also on trees. Built to a design approved by BirdWatch Ireland, the boxes give the owls extra sites in which to raise their annual brood.

And in Cork the birds are taking full advantage of their new accommodation. In a recent check of three nest boxes in the farmland around the East Cork villages of Mogeely and Killeagh, Dr Alan McCarthy of Birdwatch Ireland discovered seven thriving barn owl chicks. He told the Irish Independent that the nest box project has been a resounding success in Cork.

“Year on year we're seeing more boxes have become occupied for nesting. So last year the occupancy rate was up to 25% of boxes, which for a Red-Listed species is very good, and this year we’re still getting the numbers in but so far it looks like even more boxes will be occupied,” he said.

“The project is definitely producing the goods. Without nest boxes in these modern farm buildings, there would be no suitable cavities for barn owls to nest within, so it's providing new homes for new pairs for the population to expand.”

In the past 10 years there's been an increase of around 130% in the barn owl breeding distribution in Cork, with the highest number of known nest sites in any county. In 2023, the highest density of barn owls in Ireland were recorded within a 10-kilometre square in East Cork.

It’s good news for farmers too as the owls feed on rats and mice as well as shrews and voles. A pair of barn owls can predate over 2,000 small mammals during the breeding season, Dr McCarthy said.

Science teacher and BirdWatch Ireland volunteer Donncha Ó'Teangana has built and installed around 100 barn owl nesting boxes in County Cork over the past five years, with Cork County Council providing funding for the materials. He has since had the satisfaction of seeing many of them used to raise the next generation.

“When the first box got taken, I was delighted. When you’re putting them up and nothing's happening and you're wondering, are you doing it right? Now I'm kind of disappointed when I arrive at a box and there's nothing in it!” he said.

So the picture is looking somewhat better for the barn owl, at least in Cork. This year Cork County Council will receive €8,585 from the National Parks and Wildlife Service's Local Biodiversity Action Fund for barn owl and kestrel monitoring and conservation in the county.

Even so, the barn owl remains endangered. “We need more hedgerows that are managed sympathetically with wildlife in mind, a hedgerow that isn't cut every year and where the hedge is allowed to develop flowers, seeds and berries. Just leaving a one or two-metre grass margin along the base of a hedgerow could make the world of difference by providing good hunting for barn owls,” Dr McCarthy said.