Mousa is a low-lying island, just 1.5km long, which sits on the 60° North line one mile to the East of the Shetland Mainland. Mousa is well known for its 2000-year-old well-preserved broch and the European storm petrel (Hydrobates pelagicus) colony that return each year to breed in the Broch’s tall stone walls. Now uninhabited (the last family left the island in 1853) Mousa has a long history of human history stretching back as far as the stone age. Managed as a reserve by the RSPB and grazed by Shetland sheep, the island is a haven for wildlife while continuing in its role as part of Shetland’s crofting/farming heritage.
Highlighting the island’s importance for natural heritage Mousa has multiple nature conservation designations, both national and European. The island plays host to important colonies of breeding seabirds, including the UK’s largest storm petrel colony, as well as breeding common seals and other species such as the tiny Shetland wren. Mousa’s mix coastal habitat, wet heathland, mires and grassland, as well as the broch and dry-stone dykes (walls), provide habitats for these animals to live, feed and breed in.
Broch and stone dykes on Mousa, home to the island’s large storm petrel colony Photo: Afra Skene
One of the things that makes Mousa so remarkable as a wildlife haven is the fact that the island is still entirely free of introduced predators such as rats, mice, hedgehogs and stoats, all of whom now live on the nearby Shetland Mainland. Maintaining the rodent-free status of Mousa is particularly vital for the internationally important European storm petrel population as these tiny seabirds are so very vulnerable to predation and only breed on islands that do not have rats.
European storm petrel dapples the water surface Photo: Alastair Wilson (RSPB-images)
RSPB manage Mousa as a nature reserve and have already drawn up a biosecurity plan for the island which details how the risk of introducing non-native species can be reduced. The RSPB warden and Biosecurity for LIFE staff have put in place a surveillance system to monitor for presence of invasive non-native mammal species that could cause harm to the native wildlife. The primary risk species are rats and mice as they can travel easily as stowaways on visiting boats or in cargo/baggage. The main detection methods for these species are tunnels or boxes containing wax blocks that are flavoured to attract a rodent if it were to reach the island, gnaw marks left on the blocks that can be identified by the RSPB warden.
Flavoured wax blocks ready for deployment as part of biosecurity on Mousa Photo: Afra Skene
Thousands of visitors’ flock to Mousa each summer to see both the wildlife and the broch, travelling to the island via commercial ferry, tour company and private vessels from the nearby Shetland Mainland and by expedition cruise ships. Biosecurity for LIFE staff are working with the RSPB to create an interpretive trail for Mousa highlighting both the island’s special wildlife and the importance for biosecurity precautions. We hope to have this up and running by June 2020, watch this space!
For more information on Mousa and how to responsibly visit check out the follow websites:
RSPB Mousa: https://www.rspb.org.uk/reserves-and-events/reserves-a-z/mousa/
The Mousa Broch: https://www.historicenvironment.scot/visit-a-place/places/mousa-broch/
The Mousa Boat: https://www.mousa.co.uk/
