Numbers of one of the UK's rarest breeding ducks have almost halved in the past decade, a survey has revealed.
Experts said urgent action was needed to save the rare duck
The breeding population of the common scoter is now found only in remote freshwater lochs in northern Scotland.
There are just 52 pairs left in the country, according to research carried out by the RSPB.
The distinctive jet black diving ducks were last surveyed in 1995, but a follow-up last year found they had declined by 45%.
The reasons for the drop were unclear, but one possibility is that climate change could be pushing the birds, which have disappeared entirely from Loch Lomond and Northern Ireland, further north.
RSPB research biologist Mark Eaton said: "A decline of this nature highlights precisely the gravity of the situation facing common scoters in the UK right now.
"For this to have occurred in such a short time period is rare and of great concern."
Almost 330 Scottish lochs were surveyed for common scoters, which are also found in the Arctic and Scandinavia, during the breeding period between April and June 2007.
Islay was hardest hit, with just one pair of common scoters left, while the population in west and south Scotland dropped by 46% to 25 pairs.
The most resilient area was the Flow Country, an expanse of peatland and wetland in northern Scotland, where there were 26 pairs.
But numbers in the area had still fallen by 28% in the last 12 years.
Peter Cranswick, of the Wildfowl and Wetlands Trust, said the decline was "especially worrying", adding: "These new results clearly demonstrate that urgent action is needed to avoid the same fate befalling the remaining birds in Britain."