A rare bird of prey, tagged on the Isle of Man two years ago, has gone missing in North Wales, the RSPB has said.
The Manx-born hen harrier named Aalin was satellite tagged in 2016 as part of an EU-funded conservation project.
The charity said data from January showed the bird had settled in moorland around Ruabon Mountain near Wrexham.
It added that the harrier's satellite stopped transmitting last month and, despite a comprehensive search, no tag or body has been found.
"It is the first suspicious loss of a bird in Wales for our project," said an RSPB spokesman.
"We believe the loss of Aalin and other recently tagged hen harriers in the UK is having a devastating impact on their conservation status."
Another charity, Manx Bird Life, said it was "heart-breaking" news.
"As well as the sudden unexplained loss of yet another magnificent bird of prey, we still know so little about the behaviour of Manx-born hen harriers," a spokesman said.
Aalin and several other hen harriers were tagged in the Harrier LIFE+ project, which was launched in 2014.
The five-year scheme aims to improve protection and public awareness in the north of England and Scotland.
Police in North Wales have joined the RSPB in appealing for information about what happened to Aalin.
It follows the death last year of two Harrier chicks tagged on the Isle of Man as part of the same project.
Siblings Grayse and Mannin were found dead on the Isle of Man and in Scotland respectively.