Barn owl numbers are falling rapidly and the bird may soon disappear from Ireland entirely unless conservation measures are taken.
The barn owl is being driven out of modern Ireland. Numbers plummeted in recent years and there may be just 250 pairs left, according to John Lusby of BirdWatch Ireland. Lusby has begun a research project on barn owls and the public are asked to help by reporting sightings.
"We need to learn more about the ecology of barn owls in Ireland to introduce measures to conserve them," says Lusby. His PhD research at University College Cork aims to do just that by radio-tracking adult males during the breeding season. "I track them at night to discover how far they range, how many times they return to feed their chicks and which habitats they hunt in."
Lusby will combine his data with small mammal and habitat surveys to reveal which habitats the owls need. "It might then be possible to bring in conservation measures, say into Rural Environment Protection Scheme (Reps) or something like that," he says.
But first he must find his owls. "It's helpful if people report sightings or areas they think might be occupied by barn owls," Lusby says. He tracked five owls last year but hopes for more this year. Barn owl pairs get together around February or March, with eggs laid in April or early May. Mother and then her chicks depend on the male to bring them food. This usually consists of small mammals like rats and mice, which the owl locates at night using its acute hearing and keen eyesight.
Barn owls are ghostly white underneath, but have mottled honey-coloured plumage above. The adults can be quite vocal around early spring. "It's an obvious and eerie call - kind of a high-pitched scream," says Lusby.
Later in the summer, the chicks can be surprisingly noisy. "People give reports of strange snoring or hissing sounds from ruined buildings and that strikes a cord immediately," says Lusby. All five barn owls tracked by Lusby roosted in castles, though the birds will also use barns, old buildings and tree cavities.
So how do you catch a barn owl? "It's a matter of figuring out where the male is roosting and devising a capture technique," explains Lusby. Generally long-handled landing nets over an exit are used, though they can also be trapped using mist nets placed along regular flight pathways. A radio-transmitter is then attached to the bird, caught under license from the National Parks and Wildlife Service.
Tony Nagle of the Irish Raptor Study Group warns that the barn owl is heading towards extinction in Ireland: "We could loose the species within the next five to 10 years if serious conservation measures are not undertaken." Lusby is investigating the causes of this decline.
"Like many other lowland farmland birds, agricultural intensification probably hasn't suited them," he says. Newer, more lethal rodenticides may also be impacting barn owls, and Lusby has appealed for barn owls carcases so he can test their livers for poisons. Barn owls in Ireland rely more on rats and mice than those in Britain, so rodenticides might be even more of an issue here. Lusby recommends warfarin-based rodenticides since it is less lethal to birds.
Barn owls may also suffer from the extension of major roadways, due to the way they hunt. The owls are attracted to roadside verges, but are susceptible to being hit by larger vehicles.
Nagle notes that the main prey species of barn owls in Britain are absent here - field vole and common shrew - so it is vital that Ireland have its own detailed studies. Lusby has already discovered than owls in Ireland range further than those in the Britain.
When BirdWatch Ireland recently revisited 105 barn owl nest sites found during the mid-1990s, it discovered that more than 70 per cent had lost their owls. Lusby says a lot of the empty sites were perfectly suitable. Ireland has some catching up to do. Britain began research on its barn owls almost two decades ago and has successfully introduced conservation measures.
Lusby's research and conservation efforts by BirdWatch Ireland should give Irish owls a chance at a comeback.
• Readers can help by contacting John Lusby about barn owls sightings, or barn owl carcases at jlusby@birdwatchireland.ie.