Mousa

Also within

Shetland County

Condition (NatureScot)

Climate exposure

This is about exposure to a nationwide pressure this habitat type carries — not a verdict on this site's own management.

Geology & landscape

Landscape processes: Coastal

Birds & fish recorded

Birds

Description

Mousa Mousa is an island lying about 1 kilometre east of Sandwick in the south Mainland of Shetland. The whole island is a SSSI, notified for its breeding colonies of Arctic tern, black guillemot, storm petrel and common seals. The storm petrel colony is probably the largest in Britain, representing perhaps up to 46% of the British and 2% of the known world population, though the species is notoriously difficult to census due to inaccessible nest sites and the fact that birds are only active at the colony during darkness. The site is designated for internationally important numbers of Arctic terns (up to 1000 pairs, 2% of GB), but the species suffers when sandeels are in short supply and numbers have been considerably lower in many recent breeding seasons. Black guillemot nest in rocky crevices around the coast. Shetland supports a significant proportion of the British population (41% recorded by Seabird 2000). Two large tidal pools at south end of the island are used by common Phoca vitulina (and grey Halichoerus grypus) seals. Over 400 common seals were regularly counted during their August moult haul-out in the past, but numbers have significantly declined since the late 1990s, with maximum counts limited to double figures in recent years. This is in line with a general decline across the whole of Shetland, and is possibly linked to sandeel shortages. In June, smaller numbers of common seals give birth on the shores of the pools.

Species mentioned