A leading conservation charity has warned that osprey breeding sites in part of the North East appear to have fallen.
Members of the public are now being urged to report sightings of the birds in Aberdeenshire to build up as accurate a picture as possible of the health of the species.
The raptors first bred in the area in the early 1990s with the number of breeding sites peaking at 23 in 2011.
RSPB Scotland said that number has now dropped to 15.
Conservation Manager Ian Francis, said: “We are sure there are local nests that we don’t know about, but we are starting to worry that the population might be beginning to decline after decades of steady increase.
“Although ospreys are one of Scotland’s largest and most characteristic breeding birds, they can be very secretive and their nests are often difficult to find.”
There are between 200 and 250 breeding pairs of ospreys in the UK, many of which are in Scotland.
The bird has struggled in the past and heavy persecutions, including Victorian egg and skin collectors, resulted in decreases in the birds populations.
It eventually became extinct as a breeding bird in Scotland in 1916, though it continued to pass through on migration routes.
The osprey recolonised naturally in 1954, and a pair has successfully nested at the RSPB’s Loch Garten reserve almost every year since 1959.
The Osprey Centre at Loch Garten, which welcomed its first chick of the season on Saturday, is one of the most famous conservation sites in the world.
Osprey nests, called eyries, are quite distinctive and as the birds are mainly site-faithful, some nests have been in use for up to 20 years.
They are made of sticks and usually sit at the tops of trees.
The birds nest in any suitable tree of woodland area, but are often found far away from rivers and lochs.
At this time of year eggs are beginning to hatch, which means parents will become more active as they start bringing food to their young.
Mr Francis added: “We are urging people to get in touch to tell us about where they have seen ospreys, particularly if they think they have spotted a nest.
“Together, we can work out whether numbers of this iconic species are really declining.”
Anyone who has spotted an osprey nest can contact RSPB Scotland on 01224 624824 or at esro@rspb.org.uk