The Norrard Rocks are a group of small uninhabited granite rocks in the north–western part of the Isles of Scilly, to the west of Bryher and Samson. In 1971 they were designated as a Site of Special Scientific Interest for their breeding seabird colonies and they are permanently closed to landings from boat passengers. The vegetation on the islands is limited by the extreme exposure and only six species of flowering plants have been recorded.
Nature reserve
The islands are largely managed as nature reserves by the Isles of Scilly Wildlife Trust, principally for breeding seabirds and grey seals. The only breeding sites for European Storm–petrel in England are on the Isles of Scilly with eleven colonies and an estimated 1475 occupied sites. There are only three small breeding colonies on the Norrard Rocks; Mincarlo, Illiswilgig and Castle Bryher with a total of 37 pairs. Other seabirds breeding within the SSSI are Fulmar, Guillemot, Lesser Black–backed Gull and Herring Gull. The rove beetle has been recorded on several of the islands.
Individual islands and rocks
The islands and rocks are listed below in decreasing order of area.
Scilly Rock is just over west of Bryher is a large rock, divided by a deep chasm into two parts with a maximum height of. Each part has a summit named North Cuckoo and South Cuckoo. Landing is difficult and only possible in calm conditions. It is reputedly the island from which the rest of the archipelago gets its name although there is no evidence or explanation for this. Puffin breed and the only plants recorded are rock sea-spurrey and oraches species.
Mincarlo
Mincarlo is the southernmost of the group west of Samson. Several species nest on the island including the largest breeding colony of Cormorant in the Isles of Scilly as well as Puffin, Great Black–backed Gull, Razorbill and Common Shag. The breeding colony of European Storm–petrel occupied 17 sites during the Seabird 2000 survey. Tree mallow, orache, common scurveygrass, rock sea–spurrey and sea beet have all been recorded. The rocks are a main pupping site for grey seal. The Arachnologist, W S Bristow visited the Isles of Scilly in 1928, 1929 and 1934 and landed on many of the uninhabited islands. On Mincarlo he recorded the following spiders; Trochosa terricola, Oedothorax fuscus, Lepthyphantes tenuis, Dismodicus bifrons, Xysticus kochi and Halorates reprobus which is associated with the nests of seabirds, especially cormorant and shag.
Illiswilgig
Several species have bred on Illiswilgig, including a small colony of only three pairs of European Storm–petrel, recorded during the Seascape 2000 survey. Plants recorded are tree mallow, thrift, sea beet, rock sea–spurrey, common scurvy grass, orache and English stonecrop. Illiswilgig is a main pupping and haul–out site for grey seal.
Maiden Bower
Only a few gulls breed on Maiden Bower and no plants have been recorded.
Castle Bryher
and The Seabird 2000 survey recorded 17 occupied sites of European Storm–petrel. Puffin and gulls also breed on the island and plants recorded are tree mallow, sea beet, rock sea-spurrey, common scurvygrass and orache.
Seal Rock
An important breeding and haul out site for grey seal and orache is the only plant recorded.
