As with many of Pembrokeshire’s islands, Grassholm is steeped in myth and has been associated with the name Gwales, a kind of magical underworld mentioned in the second Branch of the Mabinogi (a 14th century collection of Welsh myths and legends).
The legend tells of a war between Wales and Ireland, following which the seven survivors of the army of Prydein (Welsh Britain) go to Gwales, a kind of magical otherworld where their sorrows were forgotten.
They live in a royal palace for eighty years, feasting and drinking with the severed, but still living, head of Bendigeidfran (Bran the Blessed) until someone, as is the way of these things, opens the third door in the hall, the door facing Cornwall they had been forbidden to open. At this point the spell is broken, their sorrows return and they have to leave the island for reality.
If you’d like to see Grassholm Island for yourself join us on one of our Grassholm and the Celtic Deep boat trips.
This small island is twenty-two acres in size, lies ten miles offshore and is home to the fourth largest gannet colony in the world.
Accounting for 10-12% of the world population of northern gannets it is, in our opinion, one of the most spectacular sights in Pembrokeshire. Seen in the morning sunshine from the mainland on a clear day, half of it appears white and we often tease tourists that it is snowing out there!
It is actually the birds themselves, as opposed to just guano, as they have the most incredibly brilliant white plumage. In certain conditions associated with hot weather, a mirage effect can sometimes be seen where Grassholm can assume all sorts of odd shapes, including a table-top island.
Gannet nests are uniformly spaced across the island, just a neck and beak’s distance away from their nearest neighbour in every direction. This is because, whilst space is at a premium, gannets are also quite aggressive birds.
In 1802 there was no record of any gannets on Grassholm, and it is thought that, prior to their arrival, there were as many as 250,000 puffins breeding on the island.
There were so many that it is likely they became a victim of their own success and, being burrow nesters, burrowed themselves out of existence as their nests caused the thin topsoil to collapse.
It is also believed that the sheep who used to graze the island may have contributed to the collapse of the puffin burrows. The remnants of these burrows can still be seen today in small areas not inhabited by the gannets.
In 1860, twenty pairs of gannets were recorded on Grassholm; by 1905 this had risen to 300 and, when the RSPB bought the island in 1948, there were 8000 pairs on the island.
It is thought that the dramatic increase in numbers may have been due to Lundy birds leaving their colony as a result of disturbance with the building of the new lighthouse and the introduction of a fog horn.
Since 2006, Dr. Steve Voitier and his team from Exeter University have been carrying out annual data-gathering work on Grassholm, attaching tracking devices and cameras to the birds to collect information on the foraging and migration strategies of northern gannets. This work actually involves camping out on Grassholm during the summer months with the 100,000 gannets, probably the same number again in flies and large infestations of earwigs!
Gannets build their nests out of anything they find floating on the surface of the water. Historically this would have largely consisted of seaweed but sadly, in more recent years, there has been a dramatic increase in discarded plastic in the form of rope and netting being picked up and used by the birds. This can have a devastating effect on the nest’s inhabitants. Every year at the end of the breeding season, weather permitting, the RSPB and a team of volunteers will spend a day on Grassholm, when the majority of the chicks have fledged, cutting free any birds that have become entangled in their nests. A couple of times we have been lucky enough to join them on these rescue missions.
