One of the UK’s most successful breeding female ospreys is unlikely to return from her winter migration, it has been announced.

Glaslyn’s Mrs G, who should have been returning to breed at the site near Porthmadog for her 20th year, is now at least three weeks late and not expected to be seen again.

Believed to be around 23 years old, she has been breeding at Glaslyn since 2004 in the nest she and her first partner built. A total of 44 chicks successfully migrated from there under her care. Several of those have gone on to breed themselves elsewhere in the UK, making her a grandmother to at least 130 and a great grandmother several times over.

It is not known where Mrs G spent her winters, but most UK ospreys migrate to western Africa. In spring, they undertake the 3000-mile return journey to re-unite with their partners.

Bywyd Gwyllt Glaslyn Wildlife, the charity which runs the project, welcomed back her partner, Aran, on 3 April, but Mrs G wasn’t there to greet him.

“We always knew this day would come and our volunteers and many supporters have been upset that she has not returned,” said visitor centre manager, Heather Corfield. “But she has been a quite remarkable bird and has made an immense contribution to the osprey breeding programme in the UK. Thousands of people at home and abroad have avidly followed her story for almost two decades. She will always be remembered and celebrated by Glaslyn Ospreys”

It is now hoped that Aran will attract a new partner and that chicks will be seen again on the nest this summer.

Visitors to Glaslyn can see live images of the nest from cameras feeds to the visitor centre and hide. Volunteers are on hand to explain the story of the ospreys. Live images are also broadcast 24 hours a day on line throughout the season on www.glaslynwildlife.co.uk/live.

Glaslyn Ospreys is open every day of the week between 10.30am and 4.30pm until the birds migrate in September. Entry is free but the charity welcomes donations.