In a quiet County Tyrone valley on the outskirts of Plumbridge is Butterlope Farm.
Surrounded by the Sperrin Mountains, it is just 18 miles from the county town of Omagh.
And that’s where the story of how the American mink – described as an aggressive predator and threat to native wildlife – began to flourish in the wild in Northern Ireland.
Butterlope is a working farm, but also provides education and training for adults with learning disabilities and mental health issues.
Part of that is working with the poultry on the farm – on two separate occasions the farm chickens have been attacked.
Annie Mullan, manager and tutor at Butterlope, told BBC News NI: “Both times the mink killed all our hens – about a dozen each time.”
A mink attack is different from those of other predators, she said.
“You know when it’s a mink that has attacked because of the stab wounds to the neck,” she added.
Annie and her colleagues have worked hard since the attacks two years ago to make the farm’s hutch mink-proof and are of course wary.
“The first thing we do every morning is check the chickens,” she said.
Her view is that, in the interests of wider conservation, the time has come for authorities to consider controlling the mink population.
Attempts have been made to do this in other parts of the UK.
When did the American mink arrive?
American minks were introduced to Ireland in the 1950s for fur farming. Over time, some escaped and some were deliberately released.
In 1961, 30 minks escaped from a farm in Omagh – the first documented escape from a fur farm in Northern Ireland.
They soon settled in the wider countryside.
Towards the end of the decade, the Belfast Telegraph reported that the “seriousness” of their presence was felt on the banks of the River Strule.
The Duke of Abercorn, the paper reported, had lost 32 pheasant chicks and two broody hens to mink attacks on his Barons Court estate that year.
Since then, mink farming has been banned on both sides of the border, but wild American minks are now widespread on the island of Ireland, according to the National Biodiversity Data Center.
A threat to fish, as well as ducks and other birds, minks are prolific breeders. And with no natural predators, their numbers have skyrocketed.
“Minks are opportunistic predators that can impact native wildlife, as with any other invasive species,” said a spokeswoman for Stormont’s Department of Agriculture, Environment and Rural Affairs (Daera).
The department conducts its own monitoring of the estates, parks and fish farms it owns and “encourages landowners to monitor mink on their properties to protect native biodiversity”.
The department currently has no plans for a broader mink control campaign, the spokeswoman said.
Discussions have previously taken place in the Republic of Ireland about how to eradicate the mink completely. But that is out of the question because of the cost.
Ger O’Donnell, the manager of the National Parks and Wildlife Service (NPWS) in the north west, monitors the area, including the Inch Wildfowl Reserve in County Donegal, where a number of minks have been sighted in recent weeks.
“Two things set them apart from other predators,” he said.
“Firstly, they are not meant to be here, and secondly, they have a special versatility – [they are] equally at home in the water as on land.”
As predators go, he added, they are “on top of their game.”
Inch is designated a Special Area of Conservation (SPA) under the EU Birds Directive and home to curlews, corncrakes, black-headed gulls and snipe, among others.
“All waterfowl and ground-nesting birds are vulnerable to minks,” Ger said.
Trappers work during the breeding season to control the mink; other measures included the installation of a predator fence on the island.
“There was an implicit wisdom at the time that suggested that local wildlife would adapt to the presence of a new species,” he said.
“It may be too early to tell if that’s the case with minks.”
Ireland’s Department of Housing, Local Government and Heritage said controlling mink numbers is “an ongoing problem”.
The American mink is one of 78 species on the Republic of Ireland’s list of invasive alien species – that means work is being done “to manage, control and, where possible, eradicate these species”.
“The National Parks and Wildlife Service is prioritizing the protection of nationally important ground-nesting bird areas and is looking to extend these efforts to vulnerable seabird colonies as well,” a department spokesman said.
He added: “Funding provided to local authorities in Ireland under the National Parks and Wildlife Service’s Local Biodiversity Action Fund also supports mink eradication operations in some areas.”
Earlier this year, a member of the Irish Parliament called for a more radical approach.
Fianna Fáil TD (Irish MP) for Tipperary Jackie Cahill wants a bounty of €20 per tail to mink hunters.
Previously there was a €3 scheme.
At the time, Deputy Agriculture Secretary Malcolm Noonan promised to explore the feasibility of reintroducing such a scheme.