It is thought Scotland's oldest breeding osprey has left the country to migrate to West Africa for the winter.
The 27-year-old bird, affectionately known as Lady, has not been seen at the Loch of the Lowes reserve near Dunkeld since Friday and rangers are certain she has begun her migration to warmer climes.
Lady astounded rangers when she returned to the Perthshire reserve for a record breaking 22nd time in March and mated with a three-year-old "toy boy".
A spokesman for the Scottish Wildlife Trust said: "We’re confident that she’s gone now, she’s been away since Friday, so five days away from the nest. Unlike Lady who’s not satellite tagged, we have tagged her offspring, tagged as ‘Blue 44’.
"He’s still in the nest, along with his father and they’ll be around for another couple of weeks."
Rangers hope to track Blue 44 when he flies the nest.
It is not known if Lady will return to the nature reserve again next spring. She has laid an impressive 64 eggs and raised 49 chicks.