Norrard Rocks

Also within

Cornwall County Isles Of Scilly Scenic Area

Condition (Natural England)

Geology & landscape

Rock Type: Granite

Landscape processes: Volcanic / Igneous

Birds & fish recorded

Birds

Description

Description: Norrard Northern Rocks lie on the north western edge of the Isles of Scilly archipelago immediately to the west of Bryher and Samson. They comprise of a series of small uninhabited granite islands including Gweal, Scilly Rock, Maiden Bower, Castle Bryher, Illiswilgig and Mincarlo together with numerous other isolated rocks and ledges. All of the islands are low lying, reaching a maximum height of only 32 metres on Gweal and hence they are all exposed to the full force of southwest gales from the Atlantic and excessive salt spray. Shallow skeletal soils are mainly confined to the larger islands; elsewhere soils are only found in sheltered isolated pockets in the granite. These thin soils and the extreme exposure severely limits the vegetation and only six species of vascular plant have been recorded from the outer islands. Tree mallow Malva arborea is the only uncommon plant and the other plant species include thrift Armeria maritima, sea beet Beta vulgaris sp maritima, common scurvy grass Cochlearia officinalis, rock sea spurrey Spergularia rupicola and orache Atriplex spp. On some of the other islets, such as Maiden Bower, there are no flowering plants. Norrard Rocks are of particular importance for their sea bird colonies, supporting some 10 species of breeding sea birds. Mincarlo is of particular note as it supports the largest colony of cormorant Phalacrocorax carbo on Scilly. Puffin Fratercula arctica breed on Mincarlo, Castle Bryher and Scilly Rock and there is a large breeding colony of shag Phalacrocorax aristotelis throughout Norrard Rocks. Other breeding sea birds include fulmar Fulmarus glacialis, razorbill Alca torda, guillemot Uria aalge, great black backed gull Larus marinus, lesser black backed gull L. fuscus and herring gull Larus argentatus. There are also records of storm petrel Hydrobates pelagicus breeding on Mincarlo. The isolated rocks and islands of Norrard Rocks are one of the most important breeding sites on Scilly for grey seal Halichoerus grypus. In addition the nationally restricted rove beetle Omalium allardii has been recorded on several of the islands in this part of the archipelago.

Species mentioned