With conditions so harsh that its last human occupants quit a century ago, the archipelago of St Kilda is a haven for wildlife, and home to some of the UK’s most precious species.

For those who to visit its abandoned street and hillside cleits, the seemingly battle-hardened sheep that roam its landscape may appear as another curiosity that make St Kilda so special; while for scientists who have spent decades recording them, they are a living research tool with pure genes that may hold the key to a range of animal health mysteries.

Now, however, two vets who live and work 40 miles across the water in the Outer Hebrides have flagged up concerns that the Soay sheep of St Kilda are the unfortunate victims of a string of anomalies that have left them fighting for survival in a real-life, deadly ‘hunger games’.

They say with no-one taking responsibility for their management – and, curiously, a relatively recent decision by Scotland’s chief vet that means they are not covered by the animal health and welfare laws that protect every other UK sheep – St Kilda’s feral flocks have been left to endure miserable illnesses, torment from parasites and starvation leading to “staggeringly high” deaths.

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Over a 20-year period, the vets say more than 12,000 adult sheep and more than 4,000 lambs have died.

Increasingly frustrated that the animal welfare standards they and other vets must comply with seem not to extend to St Kilda’s sheep, Uist-based vets David Buckland and Graham Charlesworth have now highlighted the animals’ plight and urged steps be taken to halt their suffering.

They say despite having raised their concerns with the National Trust for Scotland, which was bequeathed St Kilda in 1957 and which lists the Soay sheep on its website as among the World Heritage Site’s unique species, the conservation charity has “failed to accept any responsibility” for their welfare.

They have also questioned the work of the Edinburgh University-led St Kilda Soay Sheep Project. It has tracked the population dynamics of the sheep since the 1980s, including years which have seen up to 70% of their numbers wiped out due to illness and starvation.

Just as NTS has for years adopted a ‘hands off’ approach to the sheep, the research project relies on them being left to their own devices – leaving the two vets pondering whether the existence of the research project lends “an air of respectability” to the charity’s approach, sealing the sheep’s miserable plight.

The issue also left the vets questioning where the sheep – and, indeed, the charity – stood under animal health and welfare laws designed to protect animals from neglect and unnecessary suffering.

However, when they raised the issue with Scotland’s Chief Veterinary Officer, Sheila Voas, the pair say they were taken aback by her response which classed the St Kilda flock in the same manner as wild animals.

It makes the Soay sheep of St Kilda, the only sheep in the United Kingdom not protected by the Animal Health and Welfare Act (AHW Act).

While her description of the sheep as “an accident of history” and “of a distinct kind… not commonly domesticated in the British Islands” has particularly perplexed the vets, who described it as “bizarre” and maintain that as Ovia aries aka domestic sheep, they come from several thousands of years of domestication.

“It is their reproductive physiology, a legacy of domestication, that makes them so unsuited to life unmanaged on North Atlantic islands with no predators, competing grazers and no means of seasonal dispersal,” they say.

“Mass starvation is likely to a relatively recent recent phenomenon and a consequence of ir unmanaged state.”

The decision to regard the sheep in the same way as unowned and unmanaged wild deer, which has been confirmed by the Scottish Government, appears to contradict its own guidance for the AWH Act, which specifically includes feral sheep, goats and ponies for protection.

The two vets work in a practice on Uist and Barra from where, on a clear day, they can see the chain of uninhabited islands 40 miles north-west of the Outer Hebrides.

In 1930, amid dire living conditions, the remaining islanders were evacuated from Hirta, the largest island of the St Kilda archipelago, along with their cattle and sheep.

Within a few years, the then proprietor of St Kilda, the Earl of Dumfries, transferred 107 Soay breed sheep from neighbouring Soay to Hirta, with plans to establish a wool production enterprise.

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That collapsed, and with no management to keep numbers down, the population grew to more than 1,300 before crashing dramatically in 1961 due to starvation and parasitism.

Since then, the population has followed a pattern of recovery and crash, with numbers fluctuating between 600 and 2,300.

However, the vets say the worst population crashes, which occur when a harsh winter means there is not enough food to sustain the flock, has seen up to 70% of the sheep die.

Similar cycles of ‘boom and bust’ play out among the feral sheep populations on the other islands of the archipelago, Boreray and Soay.

“We are well aware that on mainland hill farms a few sheep may die in winter, but by comparison, the scale of the losses on St Kilda is staggering,” they say.

“These exceptionally high rates of mortality have been known about since the first study of the sheep over 60 years ago. How is that acceptable?”

They say removing some of the sheep every couple of years for sale to rare breed flocks would help keep numbers at a sustainable level.

However, that is not part of the National Trust for Scotland’s 2012 management plan for St Kilda, which states there is a “deliberate policy of non-management of the flock”. It would also be contrary to the research project’s requirement that the sheep are left to natural selection.

“As owners and managers of the land with a management plan for the sheep, it is not unreasonable to expect that they should be responsible for their welfare,” add the vets.

“Every other sheep in the UK is protected by AHW legislation. Why, especially given their well-documented starvation, would the Scottish Government choose to make a special case of the St Kilda sheep by excluding them?

“The starvation and the associated suffering of the sheep on St Kilda represent a failure by the establishment — those very institutions that should be leading the way in animal welfare.”

A National Trust for Scotland spokesperson said: “The Soay sheep of Hirta, St Kilda, originate from the population on the island of Soay where they were treated as a wild population for hundreds of years, unmanaged save for periodic hunting by the archipelago’s inhabitants.

“A small population were introduced to Hirta from Soay in the early 1930s, after the islands were abandoned and prior to the islands’ coming into the care of the National Trust for Scotland.

These too are treated as a feral population, like other wild animals they suffer mortality over the winter months.

“The sheep are an important part of the archipelago’s heritage. The persistence of the primitive breed of Soay sheep, free from genetic input from modern breeds, is one of their remarkable features, and marks them out as a potentially significant genetic resource.”

They added: “As a conservation charity, the National Trust for Scotland takes responsibilities relating to animal welfare seriously and always follows relevant legislation.

“The sheep will continue to be treated as feral animals with a presumption against intervention, except in exceptional circumstances, such as a serious outbreak of disease that threatens the sheep populations.

“The sheep were confirmed by the Scottish Government as non-native species in 2020.

“The Trust will continue to comply with Scottish Government legislation relating to St Kilda’s sheep populations.”

Meanwhile, the University of Edinburgh said the Soay sheep project had made “ground-breaking discoveries” about population dynamics and evolution by natural selection, and insights into how wild animals age and respond to climate change.

It added that the work is conducted under all appropriate licenses, and internationally recognised as one of the most important projects of its kind in the world.

A spokesperson said: “In the study area, which covers one third of the island, it is extremely rare for mortality to reach 70% in any year and this level has not been seen for many years.

“In common with most wild species that are not managed, for example the puffins of St Kilda, mortality is highly variable from year to year and falls mainly on juveniles.

“Many Soay sheep on St Kilda live much longer lives than farmed domestic sheep.”

A Scottish Government spokesperson said: “Sheep found on St Kilda are considered to be living in a wild state.

“They are considered an unowned and unmanaged population of wild animals much like other species such as wild deer.

“We recognise that within any wild population there will be different challenges from year to year; and for the St Kilda sheep we have reached that time of year where most natural deaths occur due to harsher climatic conditions.”