Monks used to visit Llanddwyn en route from Ireland to Bardsey
In 2011 RSPB Cymru celebrates 100 years of working for wildlife in Wales.
The bird charity's first connection with Wales was a bid to safeguard the future of the roseate tern on Llanddwyn Island, Anglesey, in the face of egg thieves.
Now RSPB Cymru manages 18 nature reserves and employs 150 people. But they began by hiring the services of a couple who lived in one of the old cottages on the remote island, cut off at high tide.
Elizabeth and William Jones were both qualified sea pilots who guided ships through the treacherous Menai Strait to the slate port at Y Felinheli.
However, no one could live on the island without being very close to nature, as their grand daughter, Elizabeth Llanddwyn Jones, recalled in a 2006 interview with the BBC.
"We knew she was very protective of the birds. The fewer people that went to Llanddwyn, the more likely birds would stay on the island and she wanted to keep it as a nature reserve.
"And that policy was carried out with even greater fervour after nain died."
Elizabeth remembers the cottages on Llanddwyn as being very small with rush matting on the floor to make sweeping out the sand easier.
They grew most of their own food as shopping meant a long walk over the dunes to Newborough village or a row across the Menai to Caernarfon.
One of her grandmother's few big trips away was to Buckingham Palace to be rewarded for her work with nature, and for her bravery in rowing out to rescue sailors whose boat had been wrecked on the rocks
"In a chat with the Queen Mother, she was asked 'don't you get lonely on Llanddwyn?' She said 'no, I've got the birds for company," Elizabeth recalled.
Former warden Dic Jones told the BBC: "The motto for Llanddwyn was the ringed plover. A few rare birds would come there. It was the only place on the whole of Anglesey where you'd find the snow bunting.
"There also used to be a farm there with a barn owl nesting, but I haven't seen barn owl for the last 20 years."
A small museum and information centre is housed in the Pilots' Cottages
The RSPB were unable to stop the increasing numbers of visitors coming to enjoy Llanddwyn's beach and visit the old church, dedicated to Dwynwen, the patron saint of Welsh lovers.
When the land was sold by Lord Newborough to Anglesey Council, the site ended up under the protection of the Countryside Council for Wales who run the reserve together with the neighbouring dunes and salt marshes.
"More people came to the coast for pleasure and there was more pressure on the bird population, and it still hasn't recovered," explained the reserve's current senior manager, Graham Williams.
"We get pleasure crafts, canoeists and kayakers which disturb the birds.
"The roseate terns used to nest on little islands off Llanddwyn, but in common with lots of seabirds disseminated in small pockets, they were more susceptible to attacks from gulls.
"It's always possible they could re-colonise if we get a good year."
The island is still home to grasshopper warblers, breeding cormorants and the ringed plover for which it was famous.
RSPB Cymru reserves will be hosting a series of centenary birthday celebration events throughout 2011, including the Big Garden Bird Watch on 29-30 January where the public will be asked to count which birds they can spot in their gardens.