A whimbrel ringed on a Shetland island almost a quarter of a century ago is now believed to be the world's oldest, RSPB Scotland has said.
The bird was ringed on Fetlar in 1986 and has now been identified breeding on the same island.
RSPB Scotland said it was believed to be the oldest surviving ringed whimbrel in the world, more than doubling the typical 11-year lifespan.
The previous oldest 16-year-old was shot in France in 1995.
Dr Murray Grant, principal conservation scientist with RSPB Scotland, said: "I first came across this bird 24 years ago during my PhD research on whimbrel in Shetland.
"It was probably at least two or three years old then, as that's when these birds normally start breeding, so it is a great surprise to learn that it is still revisiting Fetlar after so long."
However he explained: "My pleasure at learning of this record-breaking whimbrel is tempered by the fact that we've only found it because of our research into their population decline on Shetland.
"When I first encountered this bird there were some 80 pairs of whimbrel breeding on Fetlar, now there are probably fewer than 25.
"Sadly, it seems that this level of decline is typical of the rest of Shetland, which holds a vast majority of the UK population."
RSPB Scotland has initiated new research on the species.
Dr Grant said: "The UK population looks like it may have declined by up to 50% in the last 20 years.
"The reasons for these very rapid decreases aren't clear but we hope that our study of the species, which has started this year, will help us understand the difficulties they face.