Two young golden eagles have disappeared in suspicious circumstances on the same Scottish grouse moor, wildlife presenter Chris Packham has said.
The satellite-tagged birds were being monitored by Packham and Raptor Persecution UK as part of a study into the movements of young golden eagles in Scotland.
Adam and Charlie are said to have vanished within hours of each other from the Auchnafree Estate, near Dunkeld in Perthshire, on April 18.
The eagles' satellite tags stopped working and neither the birds nor the tags have been traced.
Packham and Raptor Persecution UK said there was no evidence to suggest the estate's involvement in the disappearances.
The Springwatch co-presenter said in a statement: "We can't prove that harm has come to Adam and Charlie, nor who might have been responsible, but we can look at the circumstances, look at the science, look at the wider evidence and draw plausible conclusions.
"The Scottish Government has already acknowledged that illegal raptor persecution is an ongoing problem.
"How many more golden eagles do we have to lose before that same Government takes effective action?"
Charlie and Adam hatched at separate nests in the Loch Lomond & Trossachs National Park in 2017 and 2018 respectively.
Adam was named and adopted by Green MSP Andy Wightman, who said he was "shocked and devastated" to hear the eagle had gone missing.
He said: "The cold rage that I felt when I heard of the circumstances of his disappearance has now developed into a determination to discover his fate.
"This latest outrage should be a wake-up call to the Scottish Government that, for all their reviews, inquiries and reforms, rampant criminality remains in place across many of Scotland's driven grouse moors."
A Scottish Government review of grouse moor management practices is expected to be published in the coming months.
Anyone with information about the disappearance of Adam and Charlie is urged to contact Police Scotland on 101 or the RSPB's confidential raptor crime hotline on 0300 999 0101.