Shrinking sheep? Ewe’ve got to be kidding me.
The average body size of the typical Soay ewe – a rare type of sheep found on a remote Scottish island – has shrunk by about five percent over the past 24 years as a result of milder winters, researchers say.
By Ben Quinn | Correspondent 07.05.09
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.”
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2. Jim | 07.05.09
Scientists study the Soay sheep on Hirta because it gives them a chance to observe what happens to an isolated population relatively free from outside influences. This type of study has much more to do with evolutionary biology and population dynamics than it has to do with agriculture and animal husbandry. Scottish farmers have no more reason to be concerned with shrinking feral ewes on Hirta than Wisconsin dairy farmers need be concerned about the average size of cow moose on Isle Royale in Lake Superior. I am baffled why a person in the domestic sheep industry would even be consulted for comment on these findings.
In closing, that photo is most certainly of domestic sheep, and not a photo of Soay sheep.
Regards,
Jim
3. Daniel | 07.05.09
Has anyone done an independent investigation into the possible link between the shrinking of the sleep and a decrease in oxygen? Pollution is a growing menace that may shut down some important processes of the Planet, and deforestation is helping either.
Peace
Dan
5. Jon | 07.05.09
5%? This is news? That’s like saying the average man is four inches shorter or taller than a generation ago.
Needed to meet a deadline, eh?
7. mmoser | 07.06.09
I guess this means that the sheep population on the island has grown substantially over the years of climate change study. For the average size to shrink 5% then you would need to increase population by 20% with lambs that are on average 30 % smaller. Boy I would sure like to see the data. Looks fishy to me.
8. Chad | 07.06.09
Um, milder winters should have cause less stress on the vegetation and allow for more and healthier plants during the year. This should cause more food to be available, healthier sheep, and an increase in size if anything.
What we have here are researchers ignorant of the island dwarfism phenomena well documented in the fossil record. I’ll leave to the reader whether that’s because they wanted funding for their research (yielding a corrupt result) or because they didn’t know about island dwarfism (rending the study moot).
9. g476486@bsnow.net | 07.06.09
What a joke. I suppose next that North Korean’s have gotten smaller because of climate change!
I am confident that there is at least one far more critically relevant factor than climate change that may be causing the sheep to get smaller.
My initial impressions were “Was the climate/temperature readings reliably taken each day?” And “Did those temperatures change in proportion to sheep weight?” But upon questioning these things a far more likely relevant factor hit me, “Wasn’t evolutions ’survival of the fittest’ the main reason that anything changed?” A far more relevant factor couldn’t accurately ignore “For example, in 1989, the population fell by two-thirds within 12 weeks.” where the ‘carrying capacity’ of the island was exceeded. I can only wonder if the sheep population ever stabilized since the island was evacuated of human predators, or if any island of such size can really ever number stabilize a large-mammal population. I’d like to know how sheep weight and size changed after 1989 for a few years, when the island had opportunity for vegetation regrowth to feed much less sheep. I’ll bet size and weight increased, regardless of any tangible climate change.
I look forward to any opportunity to challenge the authors to determine its accuracy on climate change being a relevant factor for the analysis one way or the other.
Thanks,
KaySea
10. Hal | 07.06.09
I saw an article about this a few days ago; the researchers said the sheep were - on average - 3.3 ounces lighter. How this equates to 5%, I don’t know, unless they were the size of squirrels to begin with.
11. Amanda M | 07.06.09
Who knew that the readers of the CSM were all trained evolutionary biologists with experience in field experiment design and statistical analysis! Amazing. I’ll have to add this fine blog under my bookmarks right next to the American Society for Microbiology and the European Society for Evolutionary Biology.
12. Ken | 07.06.09
Wow, using the same analysis/conclusions, I read in the paper the other day that more Americans are obese than at any point in history. Can I draw the conclusion that global warming is causing Americans to be more obese?
13. Erik | 07.06.09
So let me get this straight…. you geniuses think that the farmers can’t verify that fewer sheep are dying through the winter? Talk about insular reasoning practices, this blog takes the cake. Nothing but straw-man arguments.
shameful.
14. dennis | 07.06.09
To Ken, No, it is not global warming causing obesity in America. It is obese Americans causing global warming: We overweight people tend to breath heavier dramatically increasing the CO2 levels. Since every problem can be solved with regulation and taxation, we need to come up with some sort of emissions tax based on a persons’ weight. Save the planet: Hold your breath!
15. Berry | 07.06.09
Boy, you people sure are putting an awful lot of effort into not acknowledging the possibility of climate shift.
On its own, this study means relatively little.
In combination with the thousands of other studies which have taken place over the past two decades which also promote the conclusion that the climate is changing, it’s nothing to sneeze at.
If you want to look at the data, go look at the data, which is freely available for anybody of a serious-enough mindset. Don’t gripe about its absence in an online article; that’s like taking DISCOVER magazine to task for not including more graphs.
If you don’t chase down the facts, you’re the only one responsible for your own ignorance. And that’s perfectly acceptable to me; the more ignorant you are, the less I have to worry about competing against you. But don’t try to drag down the state of understanding of everybody else.
Those of us who understand climate science know what you are doing. And we laugh at you.
16. Luci Shaw | 07.06.09
Jim is right, the picture is not of Soay sheep but possibly Cheviots. It sounds like warmer weather is increasing sheep population and thus decreasing total forage. That could result in some size decrease.
17. Trebor | 07.06.09
Sounds like the fish bowl effect to me … more fish in the same space results in smaller fish? … there are probably plenty of other names for it … but it seems these days that science is heading more toward hocus pockus for the sake of ego!
18. Paul | 07.06.09
Were the sheep wet or dry when they were weighed? Are Americans obese because they have taken to eating more sheep meat? Will the sheep have shrunk and disappeared entirely by 2100 or will the global cooling we are experiencing ( thanks to Al Gore’s tireless efforts ) mean they grow into godzillas? All questions which can be endlessly researched at taxpayer’s expense.
19. Mike G in Corvallis | 07.06.09
On its own, this study means relatively little.
In combination with the thousands of other studies which have taken place over the past two decades which also promote the conclusion that the climate is changing, it’s nothing to sneeze at.
OK, how about this:
“On its own, one ghost story means relatively little. In combination with the thousands of ghost sightings which have taken place over the past two decades which also promote the conclusion that ghosts are real, it’s nothing to sneeze at.” Substitute sightings of Bigfoot, demons, leprechauns, or UFOs if you like.
Meanwhile, check out the Wikipedia entry on “insular dwarfism” and tell us why that isn’t a better explanation for the shrinking sheep than some supposed connection to “climate change.”
It’s like Homer Simpson’s view of beer: “Global Warming — is there anything it can’t do?
20. Robert | 07.07.09
No one said anything about a global change in this article. The local area over the last 30 or so years has gotten a little warmer. Less harsh winters means the runts and smaller animals have a better chance to survive, thus lower the average size of the population. This has nothing to do with evolution or global warming.
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1. Jay | 07.05.09
I’d like to see the data from this information. There are millions of other possible variables in the study. What specifically led them to conclude that climate change was the cause?
5% on a 50 lb sheep (?) would be 2.5 lbs. What if by chance half of the largest males breeding the sheep were killed by wild dogs (or largest females), this could cause bottlenecking, creating the illusion of “shrinking sheep”, where in fact, the sheep just got smaller by genetics and chance….
Show me the data and then I’ll believe your statements. You may act like a scientist, but until the journalists actually show us the data, how can we know?