LONDON – It sounds almost like the mysterious plot of a quirky children's bedtime tale. For decades, scientists have been baffled at how sheep on a remote Scottish island have apparently been shrinking.
Sadly for sci-fi fans, an explanation has now been found, and it has nothing with sheep being zapped in the night by UFOs.
Researchers conclude that climate change and its resulting milder winters and earlier springs have allowed smaller lambs to survive the harsh winters of the past on Hirta, the largest island in the St. Kilda archipelago, the remotest part of the British Isles. As a result, the average body size of the typical Soay ewe has shrunk by about five percent over the past 24 years.
Tim Coulson, a biologist at Imperial College in London who worked on the study, told BBC Radio 4 on Friday that during the summers on Hilda grass grew abundantly, but in the winter there was less forage and weaker sheep tended to die off as a result.
"Winters have got shorter, so many of the smaller ones are surviving and making it through, and they have dragged down the average size," he said. He added that there was mounting evidence from a range of species that climate change could influence body size and the timing of births.
"There are many examples of climate change having an affect on wild animals and birds but I think that this is the most convincing way that people have shown so far that climate change is influencing body size."
The team, whose research appears in the journal Science, also found that smaller sheep tended to give birth to smaller lambs, which they described as the "young mum effect."
For now, however, Scottish farmers appear less worried about the shrinking sheep of Hirta than other concerns. Dyana Webb, Communications Manager at the National Sheep Association, which represents the interests of the sheep industry across the United Kingdom, said she had recently returned from an event in Scotland.
"The key issue for farmers is increasing regulation and an electronic ID scheme for sheep, which farmers will find it extremely difficult to implement," she said. "No one is talking about the weather."