Soay Sheep: Natural ‘survival of the fittest’ cycle. Pic: © arjecahn
Hundreds of rare sheep are dying after a series of Atlantic storms blasted the Western Isles.
The mass deaths could see up to 60% of the 2000 Soay sheep on St Kilda wiped out over the next few weeks.
Researchers do not know the full cause behind the phenomenon but previous studies suggest a range of factors – including hunger, age and weather – which coincide at the same time.
The present population of Soay sheep is at a record high and competition for grazing means food shortages and sheep left weaker, more hungry and more at risk.
A lack of grass and the persistent onslaught of gales and heavy rain has also combined to severely affect malnourised pregnant sheep, many of which die before they have a chance to give birth.
The phenomenan is considered a natural “survival-of-the-fittest” cycle which happens every few years.
Dr Richard Luxmoore, senior nature conservation adviser at the National Trust for Scotland, said: “The fitter and better sheep will survive.
“This happens about every five to seven years. The number of sheep fluctuate quite regularly.
“There is a normal build-up over a number of years and then a population crash and the numbers drop to a low level before building up again.”
The small and dark-woolled Soay sheep are descendants of a primitive breed from the Bronze Age and are one of the most primitive breeds in the world.
On St Kilda they are a feral flock and roam wild on the 250-acre exposed island of Soay. They have no predators.
Researchers study them to find out more about the natural evolution of sheep when they are left to live and die with little human contact.
Dr Luxmore said: “We are not worried about this. It is a very important factor in maintaining the characteristics and quality of the wild breed.”
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Stormy weather killing hundreds of rare sheep