North Ronaldsay sheep

North Ronaldsay Sheep
Conservation status Vulnerable
Country of origin Scotland
Use Wool
Traits
Weight Male: 30 kg
  Female: 30 kg
Height Female: 41 cm
Wool color White, grey, brown, black
Horn status Horned
Sheep
Ovis aries

The North Ronaldsay is a breed of sheep living on North Ronaldsay, the northernmost island of the Orkney Islands, Scotland. They are one survivor of a type of sheep formerly found across the islands of Orkney and Shetland (the other is the Shetland), belonging to the Northern European short-tailed sheep group of breeds. They are seen as very close the original prehistoric North European short tail breed. They are smaller sheep than most, with the rams (males) horned and ewes (females) typically hornless. This breed is raised primarily for wool.

The semi-feral flock on North Ronaldsay is the original flock that had to evolve to live almost entirely on seaweed, as they are confined to the shoreline by a 6 feet (1.8 m) tall dry-stone wall which encircles the whole island. This was built to preserve the land for farming. The flock on North Ronaldsay is the largest flock of the breed currently, with smaller flocks on the island of Linga Holm and mainland Scotland. .

The Rare Breeds Survival Trust lists this breed as "vulnerable," with less than 600 registered breeding females in the United Kingdom.

Characteristics

Physical

They are physically a very small sheep breed, which is an adaptation typically of animals in harsh, cold environments. Rams typically weigh around 30 kilogrammes, and ewes rarely exceed 25 kg, and stand around 41 centimeters high at the withers (shoulders).[1]

The North Ronaldsay is a descendant of the primitive European Short Tailed sheep breed. As the name of the descent parent would suggest, they do have naturally short tails. Rams are all horned. These horns are typically ridged and spiraled.[2] However, only 20 percent of the ewes are horned, the rest are polled.[3]

Diet

A large herd of North Ronaldsay on the beach, exhibiting many different coat colours: white, brown, grey and black.
A herd of North Ronaldsay sheep on the beach in North Ronaldsay.

The North Ronaldsay sheep are noted for their incredibly unusual diet, almost consisting solely of seaweed. Apart from a lizard, native to the Galapagos Islands, they are the only known animal to do this.[4] The sheep have been studied for this, and it has been observed that due to preference and availability, they mainly eat brown kelps. This led to suggestions that this may be of use as an alternative food source for other livestock.[5]

The grazing habits of the sheep have also adapted to their unusual diet: instead of grazing during the day and ruminating at night as other sheep generally do, the North Ronaldsays graze as the tide reveals the shore (twice in 24 hours), ruminating at high water. The sheep's source of fresh water is limited to the few freshwater lakes and ponds along the seashore.[6]

Scientific Analysis

The sheep have evolved a somewhat different physiology from other sheep, due to their unusual diet – their digestive system has adapted to extract the sugars in seaweeds more efficiently.[3] A 2005 study at the University of Liverpool found that they have an increased susceptibility to toxicity to the trace element copper, when compared to a more traditional breed, such as the cambridge.[7] This is because their unusual diet has forces them to adapt to extract copper more efficiently, which results in normal levels of copper, which is toxic harming the sheep.[1][8] Studies suggest that they are can extract four times more copper from their diet than more traditional breeds.[9]

Also, the sheep have been studied to find that they have higher carbon 12 : carbon 13 ratio (δ13C) levels. Radiocarbon dating has showed a δ13C level of −13‰ (13 parts per thousand) which far exceeds that of any breed of grass fed sheep. This is because their diet has a far greater δ13C content than that of grass.[10]

Meat

Due to their unusual diet, the lamb and mutton from the sheep has been specially designated by the UK Government. The unique, rich flavour of the meat, which has been described as "intense and almost gamey" comes from their very iodine rich diet and traditional methods of raising the sheep.[11] Their protected status by the UK Government as 'Orkney Lamb' means that only pure-bred sheep, which have produced pure bred lambs, can be marketed as 'Orkney Lamb'.[12]

Wool

Due to their slight size, North Ronaldsay sheep were historically raised for their wool. It comes in a variety of colours, and is very similar to the Shetland breed, due to their common ancestor. More common typical colours are the whites and greys, but browns, beiges and blacks, where the hair tends to be coarser, are all exhibited.[13] A full fleece will weigh around 1 kg.[1][14]

The North Ronaldsay is a double coated breed of sheep, meaning that they have an undercoat and overcoat of wool.[15] The undercoat tends to be more fine and soft, suitable for garments that would touch the skin, whereas the overcoat is more coarse, with long hair that protects the sheep from the cold, wet weather of their natural environment. This fibre is more durable and tends to be used in overgarments.[16]

History

Prehistory

The sheep are very close physically to the North European Short tailed breed of sheep, dating back into the early history of domestication.[17] DNA studies comparing the genetics of the North Ronaldsay with the North European Short Tailed, found on the Skara Brae site which dates from around 3000 BCE, have shown a very close match.[16] Similar studies on North Ronaldsay have shown similar results.[15]

Enclosure

In 1832, a dry stone wall, known as a dyke, was erected to confine the sheep to the inside of the island, protect the seaweed on the shore, that would be harvested for iodine extraction. However, this became uneconomical, and the sheep were banished to the outside of the dyke to prevent them from wandering onto fields, or crofts and to make way for more valuable cattle.[3][18][19] It also reduces the chances of unintentional cross-breeding, which would damage the gene pool of an already vulnerable breed.[20] This dyke circles the whole of the coast of the island, and is 2 meters (12–13 ft) high, which makes it the largest single drystone entity in the world. It is an 'A' listed structure by Historic Scotland.[21]

Conservation

The North Ronaldsay Sheep Fellowship is the primary organisation concerned with the survival of the breed and they maintain the flock book (the breed registry containing all regressed purebred animals). This reports that there are less than 600 breeding females, and less than 3700 sheep in total.[22] The Rare Breeds Survival Trust (RBST), list the North Ronaldsay as "vulnerable".[23]

There are only 2 main populations of the breed, one on the island of North Ronaldsay itself, and the other was established in 1974. This was when the RBST took 178 sheep off the island and attempted to establish new populations. One group of sheep went to the mainland, and the other went to the uninhabited island of Linga Holm.[24] The RBST purchased this island and sent 150 sheep there. This was to diversify the population's geographic locations to protect from potential natural disatsers, such as an oil spill; North Sea oil extraction was expanding.[25][26]

See also

References

  1. 1 2 3 Porter, Valerie; Alderson, Lawrence; Hall, Stephen J. G.; Spoonenberg, Phillip (2016). Mason's World Encyclopedia of Livestock Breeds and Breeding. CABI. pp. 872–4. ISBN 9781845934668.
  2. ↑ "FAO Livestock Database". FAO — United Nations. Retrieved 3 December 2016.
  3. 1 2 3 Janet Vorwald Dohner (2001). The Encyclopedia of Historic and Endangered Livestock and Poultry Breeds. USA: Yale University Press. pp. 96–7. ISBN 9780300138139.
  4. ↑ Ruggeri, Amanda (24 September 2015). "BBC Earth — North Ronaldsay Sheep". bbc.co.uk. Retrieved 2 December 2016.
  5. ↑ Hansen, H. R. (2003). "A qualitative and quantitative evaluation of the seaweed diet of North Ronaldsay sheep". Animal feed science and technology. 105 (1–4): 21–28. doi:10.1016/S0377-8401(03)00053-1.
  6. ↑ "Caithness Island". Retrieved 2 December 2016.
  7. ↑ S Haywood; D M Simpson; G Ross; R J Beynon (Aug–Oct 2005). "The greater susceptibility of North Ronaldsay sheep compared with Cambridge sheep to copper-induced oxidative stress, mitochondrial damage and hepatic stellate cell activation". J. Comp. Pathol. University of Liverpool, Department of Veterinary Pathology. 133 (2–3): 114–27. doi:10.1016/j.jcpa.2005.02.001. PMID 16099232.
  8. ↑ Roussel, A. M.; Favier, A. E.; Anderson, R. A. (2006). Trace Elements in Man and Animals 10. Springer Science & Business Media. pp. 723–8. ISBN 9780306474668.
  9. ↑ Alderson, Lawrence (1978). The Chance to Survive: Rare Breeds in a Changing World. University of Minnesota: Cameron & Tayleur. pp. 76–80.
  10. ↑ Bowman, Sheridan ([1990] 1995). Radiocarbon Dating. London: British Museum Press. pp. 20–23. Check date values in: |date= (help)
  11. ↑ Hollweg, Lucas (3 February 2008). "The Virtues of North Ronaldsay Lamb". The Sunday Times.
  12. ↑ "Product Specification - "Orkney Lamb"" (PDF). gov.uk. DEFRA. Retrieved 2 December 2016.
  13. ↑ Elewes, Henry (2016). Guide To The Primitive Breeds Of Sheep And Their Crosses On Exhibition At The Royal Agricultural Society's Show, Bristol 1913. England: Read Books. ISBN 9781473352018 – via Google Books.
  14. ↑ Ekarius, Carol; Robson, Deborah (2013-08-27). The Field Guide to Fleece: 100 Sheep Breeds & How to Use Their Fibers. Storey Publishing. ISBN 1603429263.
  15. 1 2 Blacker, Susan (2012). Pure Wool: A Guide to Using Single-Breed Yarns. Stackpole Books. ISBN 9780811760959 – via Google Books.
  16. 1 2 Ekarius, Carol; Robson, Deborah (2013). The Field Guide to Fleece: 100 Sheep Breeds & How to Use Their Fibers. Storey Publishing. pp. 146–7. ISBN 9781603429269 – via Google Books.
  17. ↑ Long, John L. (2003). Introduced Mammals of the World: Their History, Distribution and Influence. Csiro Publishing. p. 527. ISBN 9780643099166 – via Google Books.
  18. ↑ "A historic Introduction". The Native Sheep of North Ronaldsay. Sheep-Isle. Retrieved 2009-04-23.
  19. ↑ Duke, Charile (12 October 2015). "Dyke under threat". Daily Record. Retrieved 2 December 2016.
  20. ↑ "Seaweed Sheep get their own festival". Press and Journal. 11 May 2016. Retrieved 2 December 2016.
  21. ↑ "North Ronaldsay Dyke Information". Buildings At Risk Scotland. Retrieved 2 December 2016.
  22. ↑ "North Ronaldsay Sheep Fellowship". Retrieved 2 December 2016.
  23. ↑ Watchlist 2014,The Ark (RBST quarterly magazine), Spring 2014
  24. ↑ "Rare Breeds Survival Trust breed profile". Rare Breeds Survival Trust. Retrieved 2 December 2016.
  25. ↑ National Research Council (1993). Managing Global Livestock Genetic Resources. National Academies Press. pp. 28, 101. ISBN 9780309043946.
  26. ↑ "Scottish Places — Linga Holm". Retrieved 2 December 2016.
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