
Skomer () or Skomer Island is an island off the coast of
Pembrokeshire, in the community of
Marloes and St Brides
Marloes and St. Brides (Welsh: ''Marloes a Sain Ffraid'') is a community in the West Wales county of Pembrokeshire.
The main settlements are the villages of Marloes and St Brides. Both villages lie on the southern shore of St Brides Bay
The ...
in west Wales. It is well known for its wildlife: around half the world's population of
Manx shearwater
The Manx shearwater (''Puffinus puffinus'') is a medium-sized shearwater in the seabird family Procellariidae. The scientific name of this species records a name shift: Manx shearwaters were called Manks puffins in the 17th century. Puffin is an ...
s nest on the island, the
Atlantic puffin
The Atlantic puffin ('), also known as the common puffin, is a species of seabird in the auk family. It is the only puffin native to the Atlantic Ocean; two related species, the tufted puffin and the horned puffin is found in the northeaster ...
colony is the largest in southern Britain, and the
Skomer vole (a subspecies of the
bank vole
The bank vole (''Myodes glareolus'') is a small vole with red-brown fur and some grey patches, with a tail about half as long as its body. A rodent, it lives in woodland areas and is around in length. The bank vole is found in much of Europe an ...
) is unique to the island. Skomer is a
national nature reserve, a
Site of Special Scientific Interest and a
Special Protection Area
A Special Protection Area (SPA) is a designation under the European Union Directive on the Conservation of Wild Birds. Under the Directive, Member States of the European Union (EU) have a duty to safeguard the habitats of migratory birds and cert ...
. It is surrounded by a
marine nature reserve and is managed by the
Wildlife Trust of South and West Wales
The Wildlife Trust of South and West Wales (WTSWW) ( cy, Ymddiriedolaeth Natur De a Gorllewin Cymru) is a Wildlife Trust in south and west Wales, one of 46 such Trusts in the United Kingdom.
History
Forerunner of the WTSWW, the former West W ...
.
Skomer is known for its archaeological interest:
stone circle
A stone circle is a ring of standing stones. Most are found in Northwestern Europe – especially in Britain, Ireland, and Brittany – and typically date from the Late Neolithic and Early Bronze Age, with most being built from 3000 BC. The ...
s,
standing stone
A menhir (from Brittonic languages: ''maen'' or ''men'', "stone" and ''hir'' or ''hîr'', "long"), standing stone, orthostat, or lith is a large human-made upright stone, typically dating from the European middle Bronze Age. They can be fou ...
and remains of prehistoric houses. Much of the island has been designated an
ancient monument
In British law, an ancient monument is an early historical structure or monument (e.g. an archaeological site) worthy of preservation and study due to archaeological or heritage interest. The '' Ancient Monuments and Archaeological Areas Act ...
.
Description
The island has an area of .
Its highest point is above sea level at Gorse Hill, while the majority of the island sits at around above sea level. Skomer is intersected by a series of slopes and ridges giving it a rich and varied topography. It is approximately from north–south and east–west.
The island is almost cut in two near its eastern side by two bays. It is one of several islands lying within a kilometre of the
Pembrokeshire coast. A number of islets surround Skomer, the largest of which are:
Midland Isle
Middleholm, also known as Midland Isle, is a small island lying off southwest Pembrokeshire in Wales, between the island of Skomer and the mainland in the Community (Wales), community of Marloes and St Brides. It is roughly circular with a diamet ...
(height 50 metres, 164 feet) separated from Skomer by Little Sound, Mew Stone (60 metres, 197 feet) and Garland Stone (32 metres, 105 feet).
Name
The name Skomer derives from ''Skalmey'', a name of Viking origin meaning "Cleft island", possibly from the fact that the eastern end of the island is nearly cut off from the main part.
It is marked on a 1578 map in Latin as ''Scaline Insul'', with the first word probably meaning ''scalene'' or ''unequal''.
Geology
The volcanic rocks of which Skomer is comprised date from the
Silurian
The Silurian ( ) is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at million years ago (Mya), to the beginning of the Devonian Period, Mya. The Silurian is the shortest period of the Paleozoi ...
period around 440 million years ago. A series of
basalt
Basalt (; ) is an aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the surface of a rocky planet or moon. More than 90% of a ...
s,
rhyolite
Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained ( aphanitic) in texture, but may be porphyritic, containing larger mineral crystals ( phenocrysts) in an otherwise fine-grained groundmass. The min ...
s,
felsite
Felsite is a very fine-grained volcanic rock that may or may not contain larger crystals. Felsite is a field term for a light-colored rock that typically requires petrographic examination or chemical analysis for more precise definition. Color ...
s,
keratophyre
Keratophyre is a volcanic rock of intermediate composition. Although similar to trachyte, keratophyre's plagioclase component is richer in sodium than the plagioclase found in trachyte. Keratophyre forms lava flows and subvolcanic intrusions ...
s,
mugearite
Mugearite () is a type of oligoclase-bearing basalt, comprising olivine, apatite, and opaque oxides. The main feldspar in mugearite is oligoclase.
Mugearite is a sodium-rich member of the alkaline magma series. In the TAS classification of v ...
and associated
sedimentary
Sedimentary rocks are types of rock that are formed by the accumulation or deposition of mineral or organic particles at Earth's surface, followed by cementation. Sedimentation is the collective name for processes that cause these particles ...
rocks (
quartzite
Quartzite is a hard, non- foliated metamorphic rock which was originally pure quartz sandstone.Essentials of Geology, 3rd Edition, Stephen Marshak, p 182 Sandstone is converted into quartzite through heating and pressure usually related to tec ...
s, etc.) are grouped together as the 'Skomer Volcanic Series'. The series which is up to 1000m thick also includes
trachyte
Trachyte () is an extrusive igneous rock composed mostly of alkali feldspar. It is usually light-colored and aphanitic (fine-grained), with minor amounts of mafic minerals, and is formed by the rapid cooling of lava enriched with silica and ...
,
dolerite
Diabase (), also called dolerite () or microgabbro,
is a mafic, holocrystalline, subvolcanic rock equivalent to volcanic basalt or plutonic gabbro. Diabase dikes and sills are typically shallow intrusive bodies and often exhibit fine-grained ...
and
skomerite which is an altered
andesite
Andesite () is a volcanic rock of intermediate composition. In a general sense, it is the intermediate type between silica-poor basalt and silica-rich rhyolite. It is fine-grained (aphanitic) to porphyritic in texture, and is composed predomina ...
. Basalt is the most common component of this sequence; some of it appears as
pillow lava
Pillow lavas are lavas that contain characteristic pillow-shaped structures that are attributed to the extrusion of the lava underwater, or ''subaqueous extrusion''. Pillow lavas in volcanic rock are characterized by thick sequences of disconti ...
indicating that it was erupted under water. Other basalt flows show signs of contemporary
subaerial In natural science, subaerial (literally "under the air"), has been used since 1833,[Subaerial](_blank)
in the Merriam ...
weathering
Weathering is the deterioration of rocks, soils and minerals as well as wood and artificial materials through contact with water, atmospheric gases, and biological organisms. Weathering occurs '' in situ'' (on site, with little or no movemen ...
.
This same suite of rocks can also be traced eastwards on the mainland along the northern side of the Marloes peninsula and extends almost as far east as
St Ishmael's. The entire sequence on Skomer dips between 15° and 25° to the south-southeast. It is cut by several
faults, notably those responsible for the erosion of the inlets of North Haven and South Haven. A NW-SE aligned fault stretches between Bull Hole and South Haven, offsetting the strata on either side.
Skomer was cut off from the mainland by rising sea levels after the last Ice Age.
History

There is evidence of human occupation—field boundaries and settlement remains—dating back to the
Iron Age
The Iron Age is the final epoch of the three-age division of the prehistory and protohistory of humanity. It was preceded by the Stone Age (Paleolithic, Mesolithic, Neolithic) and the Bronze Age (Chalcolithic). The concept has been mostly appl ...
.
The Skomer Island Project, run jointly by the Royal Commission for Ancient and Historical Monuments in Wales (RCAHMW) with archaeologists from the University of Sheffield and Cardiff University, started in 2011, investigates the island's prehistoric communities. Airborne laser scanning together with ground excavations continued in 2016 and established that human settlement dates back 5,000 years. Rabbits were introduced in the 14th century and their burrows and grazing have had a profound effect on the island landscape.
It was last permanently inhabited by the Codd family (all year round) in 1950. After the
Second World War
World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the World War II by country, vast majority of the world's countries—including all of the great power ...
, the owner had offered the West Wales Field Society, now
The Wildlife Trust of South and West Wales, the opportunity to make a survey of Skomer which was accepted and Skomer opened for visitors from April 1946. The farm buildings in the centre of the island, now housing visitor accommodation, were refurbished in 2005.
Skomer was featured in the BBC TV documentary ''
Coast
The coast, also known as the coastline or seashore, is defined as the area where land meets the ocean, or as a line that forms the boundary between the land and the coastline. The Earth has around of coastline. Coasts are important zones in n ...
'' in Episode 4 of Series 5 (first aired August 2010).
David Saunders MBE was in 1960 the first warden of Skomer.
Wildlife
Skomer is best known for its large breeding
seabird
Seabirds (also known as marine birds) are birds that are adapted to life within the marine environment. While seabirds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent evolution, as the same envir ...
population, including
Manx shearwater
The Manx shearwater (''Puffinus puffinus'') is a medium-sized shearwater in the seabird family Procellariidae. The scientific name of this species records a name shift: Manx shearwaters were called Manks puffins in the 17th century. Puffin is an ...
s,
guillemot
Guillemot is the common name for several species of seabird in the Alcidae or auk family (part of the order Charadriiformes). In British use, the term comprises two genera: '' Uria'' and '' Cepphus''. In North America the ''Uria'' species a ...
s,
razorbill
The razorbill, razor-billed auk, or lesser auk (''Alca torda'') is a colonial seabird and the only extant member of the genus '' Alca'' of the family Alcidae, the auks. It is the closest living relative of the extinct great auk (''Pinguinis i ...
s,
great cormorant
The great cormorant (''Phalacrocorax carbo''), known as the black shag in New Zealand and formerly also known as the great black cormorant across the Northern Hemisphere, the black cormorant in Australia, and the large cormorant in India, is a w ...
s,
black-legged kittiwake
The black-legged kittiwake (''Rissa tridactyla'') is a seabird species in the gull family Laridae.
This species was first described by Carl Linnaeus in his landmark 1758 10th edition of ''Systema Naturae'' as ''Larus tridactylus''. The English ...
s,
Atlantic puffin
The Atlantic puffin ('), also known as the common puffin, is a species of seabird in the auk family. It is the only puffin native to the Atlantic Ocean; two related species, the tufted puffin and the horned puffin is found in the northeaster ...
s,
European storm-petrels,
common shag
The European shag or common shag (''Gulosus aristotelis'') is a species of cormorant. It is the only member of the monotypic genus ''Gulosus''. It breeds around the rocky coasts of western and southern Europe, southwest Asia and north Africa, mai ...
s,
Eurasian oystercatcher
The Eurasian oystercatcher (''Haematopus ostralegus'') also known as the common pied oystercatcher, or palaearctic oystercatcher, or (in Europe) just oystercatcher, is a wader in the oystercatcher bird family Haematopodidae. It is the most widesp ...
s and
gull
Gulls, or colloquially seagulls, are seabirds of the family Laridae in the suborder Lari. They are most closely related to the terns and skimmers and only distantly related to auks, and even more distantly to waders. Until the 21st century, ...
s, as well as
birds of prey
Birds of prey or predatory birds, also known as raptors, are hypercarnivorous bird species that actively hunt and feed on other vertebrates (mainly mammals, reptiles and other smaller birds). In addition to speed and strength, these predato ...
including
short-eared owl
The short-eared owl (''Asio flammeus'') is a widespread grassland species in the family Strigidae. Owls belonging to genus ''Asio'' are known as the eared owls, as they have tufts of feathers resembling mammalian ears. These "ear" tufts may or ...
s,
common kestrel
The common kestrel (''Falco tinnunculus'') is a bird of prey species belonging to the kestrel group of the falcon family Falconidae. It is also known as the European kestrel, Eurasian kestrel, or Old World kestrel. In the United Kingdom, where no ...
s and
peregrine falcon
The peregrine falcon (''Falco peregrinus''), also known as the peregrine, and historically as the duck hawk in North America, is a cosmopolitan bird of prey ( raptor) in the family Falconidae. A large, crow-sized falcon, it has a blue-grey ...
s. The island is also home to
grey seal
The grey seal (''Halichoerus grypus'') is found on both shores of the North Atlantic Ocean. In Latin Halichoerus grypus means "hook-nosed sea pig". It is a large seal of the family Phocidae, which are commonly referred to as "true seals" or ...
s,
common toad
The common toad, European toad, or in Anglophone parts of Europe, simply the toad (''Bufo bufo'', from Latin ''bufo'' "toad"), is a frog found throughout most of Europe (with the exception of Ireland, Iceland, and some Mediterranean islands), in ...
s,
slow-worms, a breeding population of
glow-worms and a variety of
wildflowers.
Harbour porpoise
The harbour porpoise (''Phocoena phocoena'') is one of eight extant species of porpoise. It is one of the smallest species of cetacean. As its name implies, it stays close to coastal areas or river estuaries, and as such, is the most familiar ...
s occur in the surrounding waters. The
Skomer vole, a
subspecies of
bank vole
The bank vole (''Myodes glareolus'') is a small vole with red-brown fur and some grey patches, with a tail about half as long as its body. A rodent, it lives in woodland areas and is around in length. The bank vole is found in much of Europe an ...
, is endemic to the island.
Atlantic puffin

There are around 10,000 breeding pairs of puffins on Skomer and
Skokholm
Skokholm () or Skokholm Island is an island off the coast of Pembrokeshire, Wales, south of the neighbouring island of Skomer. The surrounding waters are a marine reserve and all are part of the Pembrokeshire Coast National Park. Both islands ...
Islands, making them one of the most important puffin colonies in Britain. They arrive in mid-April to nest in burrows, many of which have been dug by the island's large
rabbit
Rabbits, also known as bunnies or bunny rabbits, are small mammals in the family Leporidae (which also contains the hares) of the order Lagomorpha (which also contains the pikas). ''Oryctolagus cuniculus'' includes the European rabbit s ...
population. The last puffins leave the island by the second or third week in July. They feed mainly on small fish and
sand eel
Sand eel or sandeel is the common name used for a considerable number of species of fish. While they are not true eels, they are eel-like in their appearance and can grow up to in length. Many species are found off the western coasts of Europe ...
s; often puffins can be seen with up to a dozen small eels in their beaks.
After a period of declining numbers between the 1950s and 1970s, the
size of the colony is growing again at 1–2% a year (). By 2004, there were numerous puffin burrows on the island and adults flying back with food run across the walkways oblivious to the tourists. A 2019 survey estimated a population of 24,108 birds,
and in 2020 this had increased to 34,796 birds.
Manx shearwater
In 2011, an estimated 310,000
pairs of
Manx shearwater
The Manx shearwater (''Puffinus puffinus'') is a medium-sized shearwater in the seabird family Procellariidae. The scientific name of this species records a name shift: Manx shearwaters were called Manks puffins in the 17th century. Puffin is an ...
were breeding on Skomer, with around 40,000 pairs on the "sister" island Skokholm. A 2019 survey estimated the Skomer population at almost 350,000, a 10 per cent increase. The colony comprises around half the world population and make the islands the world's most important breeding site for the species. The birds nest in burrows, which they either excavate themselves or commandeer from other burrow-making species, such as rabbits. Pairs will typically use the same burrow year after year.
Shearwaters are not easy to see as they come and go at dusk, but a
closed-circuit television camera in one of the burrows allows subterranean nesting activity to be seen on the screen in Lockley Lodge on the mainland at Martin's Haven. The remains of shearwaters killed by the island's population of
great black-backed gull
The great black-backed gull (''Larus marinus'') is the largest member of the gull family. Described by the Cornell Lab of Ornithology as "the king of the Atlantic waterfront", it is a very aggressive hunter, pirate, and scavenger. It breeds on ...
s can also be seen.
The young Manx shearwaters remain at sea for five years before returning to breed on their natal island. On their return they navigate back to within a few metres of the burrow in which they were born. As they are ungainly and vulnerable on the land, they leave their burrows at dawn for the fishing grounds some fifty kilometres north out in the
Irish Sea
The Irish Sea or , gv, Y Keayn Yernagh, sco, Erse Sie, gd, Muir Èireann , Ulster-Scots: ''Airish Sea'', cy, Môr Iwerddon . is an extensive body of water that separates the islands of Ireland and Great Britain. It is linked to the Ce ...
, not returning until dusk. Thus they attempt to avoid the gulls to which they would fall easy prey.
Skomer vole
Skomer has one unique mammal: the Skomer vole (''Myodes glareolus skomerensis''), a distinct form of the
bank vole
The bank vole (''Myodes glareolus'') is a small vole with red-brown fur and some grey patches, with a tail about half as long as its body. A rodent, it lives in woodland areas and is around in length. The bank vole is found in much of Europe an ...
. The lack of land-based predators on the island means that the
bracken
Bracken (''Pteridium'') is a genus of large, coarse ferns in the family (biology), family Dennstaedtiaceae. Ferns (Pteridophyta) are vascular plants that have alternating generations, large plants that produce spores and small plants that produ ...
habitat is an ideal place for the vole, with the population reaching around 20,000 during the summer months. Then the resident short-eared owls may be seen patrolling the areas close to the farmhouse in the centre of the island for voles to feed their young.
Access

The ''Dale Princess'' sails to Skomer from
Martin's Haven on the mainland, a sheltered 15-minute trip every day (weather dependent) except Monday (Whitsun Bank Holiday Monday excepted) from April to September between 10am and noon (actual times may vary). There are limits on the number of people allowed to visit the island (250 per day). Advance booking is recommended after the introduction of a new visitor management system in 2020.
A self-catering hostel with 16 beds is situated at the farm in the centre of the island. Booking opens in October and can only be done by phoning the Tondu office. Overnight guests are brought over on a separate boat trip on the morning of their stay and the hostel is open April to September.
Areas open for visitor access are restricted to pathways. The Neck, an eastern area connected only by a narrow isthmus, is entirely out of bounds to visitors.
In 2005–06, there was a renovation project of the farm buildings which included the old barn for improved overnight visitor and research accommodation, the volunteers' quarters were rebuilt and the warden's house at North Haven was also rebuilt. Solar power provides hot water and electricity for lighting.
See also
*
Skomer Marine Conservation Zone
References
External links
Wildlife Trust of South and West WalesSkomer Marine Nature ReservePhotographs of Skomer Island on Geograph
{{authority control
Islands of Pembrokeshire
Birdwatching sites in Wales
Important Bird Areas of Wales
National nature reserves in Wales
Nature Conservation Review sites
Silurian volcanism
Uninhabited islands of Wales
Volcanism of Wales
Seabird colonies