Mousa lies a mile off the east coast of Mainland Shetland about 15 miles (24 km) south of Lerwick. Almost divided in two by inlets, East and West Hams, the island is 1.5 miles (2.4 km) long and almost 1-mile (1.6 km) in maximum width.

As Scotland entered the Iron-Age (600BC – AD500) the general feeling of unrest led to the building of a series of defensive round stone towers known as Brochs. It is unclear whether these uniquely Scottish forts were built by the invaders or the native population, but it seems they were built to provide short-term defence against siege. With limited space for the provision of stores, a few cattle could be kept within the walls and some had an in-built water supply. Although, many Brochs were built in regions routinely attacked by raiders, it is generally felt that Brochs afforded protection against a neighbour who held a grudge over a domestic dispute.

The Broch building period ended around AD100. During this later period they were probably seen as status symbols for their owners rather than for defence. The Island of Mousa has the best-preserved example of these ancient fortresses.

Mousa Broch is a little narrower than most but at a height of 13.3m it is almost unique. The tower structure is formed from two concentric stone walls that are made from local quarried stone. The entrance to the inner body is via a low passage through the walls. Once inside the tower you see a stone water tank that has been dug into the bedrock.

The diameter of the Broch is wider at the bottom as the solid base includes three oval cells. These would have provided sanctuary and ample storage facilities. As you rise up through the tower the walls become hollow. It is possible to climb a narrow spiral staircase, between the walls, which leads to the top of the Broch. As you proceed along the staircase you can peer into six galleries, which lie between the inner and outer walls. These galleries are floored and roofed with large slabs, which probably aided the stability of such a tall tower. There were gaps in the inner wall, which would allow light into these galleries, which could also have been additional storage areas. There is evidence that the Broch could have had internal wooden floors offering protection on a number of levels. It is quite possible to walk around the top of the tower and view part of the original slanting roof that would have been constructed by other large slabs. It is felt that the height of the Broch would have been chosen because it offers a slight view of the sea to the east of Mousa. This would allow the inhabitants to see any invaders before being spotted themselves.
Most Brochs have been dismantled throughout time by succeeding dwellers who found other uses for the stone. Also, living habits changed and so such structures were no longer considered practicable or desirable. However, the Mousa example has remained more or less unchanged over the last 2000 years due, largely, to its remote location.

HARBOUR PORPOISE

Mousa Sound is one of the best places in Britain to see these marine mammals. Adults give birth in the summer, when it is common to see them swimming with their new offspring feeding on the Sandeels. Their habit of coming to the surface and “snorting” has given rise to many names, the latin derivative being Porcus piscus , “pig fish” as it translates and hence porpoise today.

Locally they are known as “Neesicks” from the Norse word nisa meaning “to sneeze”

SEALS

Take a walk round Mousa to the East Pool and West Pool to see the huge population of Seals which live around the island. During the summer it is possible to see upto a hundred seals basking in the sunshine around the pools.

Common Seals are more numerous than the larger Grey Seal variety identified by their roman nose. The seals have become very accustomed to visitors so it is possible to have a great view of these magnificent creatures.

Common Seals have their young in the summer, the Grey Seals much later in the year, which gives two possible opportunities to see Seal pups on the shoreline.

Great Skua (Stercorarius skua) and Arctic Skua (Stercorarius longicaudus)

These skuas are also frequent summer visitors to the island. These are large birds and are almost unique, as they are one of the few types of sea bird that is not white. Both birds are mainly brown in colour but they can be easily distinguished from each other. The Arctic Skua or Skooty Aalin is the commonest of the small skuas and has elongated tail feathers which are straight and pointed. The much stockier Great Skua or Bonxie is larger with large white wing patches. They nest away from the coast preferring the sanctuary of adjacent moorland. They will protect nesting sites with much enthusiasm and can be seen swooping upon any potential threats. They will catch their own fish but think nothing of trying to steal fish from other, much larger, adversaries.

Storm Petrels (Hydrobates pelagicus)

The local name for these birds is the Alamootie and are abundant visitors during the summer. They are very small and are generally black with a white rump. They can be seen fluttering low over the water pausing momentarily to dip and feed from the surface. As a result of this feeding habit they have taken their name from St Peter because they appear to be able to walk on water. These small birds nest under boulders or on beaches and will even make a home for themselves inside the walls of the Broch. Care should be taken if you here strange noises within Broch walls as the Petrel will abandon its home once disturbed. The birds will take turns to guard the nest while its partner returns to sea to feed on plankton. It will return to the nest to swap duties under the cover of darkness.

ARCTIC TERNS (Sterna paradisaea)

This fragile, rather elegant bird, is another frequent visitor during the summer. They are amongst the greatest travellers within the bird community. During their 25 year life span and frequent trips between their Arctic breeding grounds and North Africa they can fly a distance equivalent to that of the moon. They are easy to spot with a distinctive black head and, during the summer, a bright red bill. They do not nest but prefer to lay their eggs a little distance inshore in natural mounds in the ground. They are very well camouflaged and you can easily find yourselves disturbing their territory. The northern half of Mousa has become a large breeding ground for the Arctic tern, known locally as the Tirrick, as the sound between the island and Sandwick has a plentiful supply of their permanent diet, the Sandeel. Once aroused the entire colony will defend its territory. They can be seen swooping from a great height to frighten any intruder. Holding a stick above your head will give you protection while you quickly leave the area.

Black Guillemot (Cepphus grylle)

There are many hundred Black Guillemots or Tysties nesting around the coast of Mousa. These distinctive black birds with large white wing patches nest in holes in the cliff or under boulders. They are reluctant flyers and much prefer to dive into the water to reach safety. It is in this environment that they feed on small fish amongst the seaweed. With very short, stubby wings they struggle to achieve flight but can dive to depths of 200 ft with a unique rib structure which gives their body tremendous strength

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