Grassholm

This article is about the island of Wales. For other uses, see Grassholm (disambiguation).

Grassholm
Native name:
Ynys Gwales
Grassholm
Map
Geography
LocationSM 597 093
Coordinates51°43′52″N 5°28′47″W / 51.7311°N 5.4796°W / 51.7311; -5.4796
Area10.72 ha (26.5 acres)[1]
Highest elevation42 m (138 ft)
Administration
United Kingdom
CountyPembrokeshire
CommunityMarloes and St Brides
Demographics
PopulationUninhabited

Grassholm (Welsh: Gwales or Ynys Gwales) or Grassholm Island[2] is a small uninhabited island situated 13 kilometres (8 mi) off the southwestern Pembrokeshire coast in Wales, lying west of Skomer, in the community of Marloes and St Brides.[3] It is the westernmost point in Wales other than the isolated rocks on which the Smalls Lighthouse stands. Grassholm is known for its huge colony of northern gannets; the island has been owned since 1947 by the Royal Society for the Protection of Birds, and is one of its oldest reserves. It reaches 42 metres (138 ft).

Grassholm National Nature Reserve is the third most important site for gannets in the world, after two sites in Scotland: St Kilda and Bass Rock. It serves as a breeding site for 39,000 pairs of the birds, and supports around 10 per cent of the world population.[4][5] The turbulent sea around Grassholm is a good feeding area for porpoises and bottlenose dolphins.

The island has a significant problem with marine plastic, brought to the island by breeding gannets, as nesting material which the birds have mistaken for seaweed floating in the surrounding waters. The problem has been ongoing through twelve years of RSPB conservation to 2017, and surveys have indicated that 80% of nests contain waste plastics.[6][7][8]

Boats sail to Grassholm from St Davids Lifeboat Station and Martin's Haven on the mainland, but members of the public are not permitted to land.[5]

Geologically, the island is largely formed from keratophyre, though the northwest coast and the islet of West Tump are formed from basalt. A couple of NE-SW aligned faults cross the island. Raised beaches are present in places.[9]

  1. ^ "SPA Description - Grassholm". Joint Nature Conservation Committee. DEFRA. Retrieved 2 March 2017.
  2. ^ "Grassholm Island". Ordnance Survey. Retrieved 7 February 2019.
  3. ^ Ordnance Survey. "SM5909". Geograph. Retrieved 16 November 2018. (click on map)
  4. ^ Anon. "Grassholm". RSPB wepages. The Royal Society for the Protection of Birds. Retrieved 11 April 2010.
  5. ^ a b "Visit Pembrokeshire: Grassholm". Retrieved 8 November 2018.
  6. ^ "Saving the birds ensnared on 'plastic island'". Euronews. 20 October 2017. Retrieved 20 October 2017.
  7. ^ "Gannets ensnared by twisted plastic around their legs on Grassholm island". Sky News. 20 October 2017. Retrieved 20 October 2017.
  8. ^ "Plastic Gannets". Autumnwatch. 19 November 2014. BBC. BBC2. Retrieved 20 October 2017.
  9. ^ British Geological Survey 1978 1:50,000 scale geological map sheet (England and Wales) 226/227 Milford (Keyworth, Notts)