An island off Pembrokeshire is celebrating reclaiming its status as a vitally important bird observatory.
Skokholm Island was the very first bird observatory to be established in Britain back in 1933.
But the researching and ringing of birds ceased in 1976.
However the island was bought by the Wildlife Trust of South and West Wales - and Sunday will see the trust realise its vision for the island to become an official bird observatory once again.
"It is vitally important, because Skokholm was the very first bird observatory ever established," explained the conservationist and Welsh wildlife expert, Iolo Williams.
"It has been some 30-plus years since that all changed, but now we can finally reopen the island as an observatory once again.
"It is a momentous occasion."
Skokholm lies 2.5 miles (4km) off the Pembrokeshire coast, and was once part of the Dale Estate.
It was leased by Cardiff-born ornithologist Ronald Lockley in 1927, and by 1933 he had turned the island into the UK's very first bird observatory.
The running of the island was taken over by the forerunner of the Wildlife Trust in 1948, and in 2007 the trust purchased the island for £600,000.
A year later, it was declared a national nature reserve, and the whole 106 hectares (260 acres) of the island is an officially designated Site of Special Scientific Interest.
Since purchasing the island, the trust and volunteers have been restoring buildings on the island, including Lockley's former cottage and the island lighthouse.
The area around the lighthouse is of international importance, as it has nearly 3,000 burrows used by Manx shearwater birds - making it almost certainly the densest shearwater colony in the world. In fact, along with nearby Skomer, the two islands are believed to be home to half the world's Manx shearwaters.
Skokholm is also an important environment for storm petrels, and for greater black-backed and herring gulls.
Regaining its observatory status means the island rejoins a network of 18 other observatories around the UK coast, including another Welsh island - Bardsey off the Llyn coast of Gwynedd.
The observatories work to record migration patterns, bird populations, and developing conservation policies and scientific research.
"To have Skokholm back as a bird observatory, it really is a landmark day for all those involved," added naturalist, Williams, who will be taking part in the official ceremony to mark the regained status for the island later on Sunday.