Rare footage of an adult otter fishing for food has been shot in an Edinburgh city centre river.
BBC Scotland news website has obtained the "exciting new video evidence" of an otter in the Water of Leith.
As they are largely nocturnal and elusive animals, experts have been relying on droppings and footprints to back up reports they are in cities.
Wildlife information officers said otters were a "very important" indicator of the health of a river.
Bob Anderson, Wildlife Information Centre biodiversity data officer, said: "I am extremely interested in this video footage because it is very rare to have an adult otter filmed as we just don't tend to see them.
"They are very elusive creatures so we normally receive reports of droppings and footprints than actual sightings.
"They are a European protected species and the more sightings we receive the better we can build up a picture of where they are.
"I would urge for people to contact me with any otter sightings in the Lothians."
Jean-baptiste Direz, 23, an Edinburgh student who is studying aquatic ecosystem management, said he was on a day field trip on 27 September, when he spotted the otter.
He said: "I was very excited when I saw it and my teacher was even more so as she said it was the first one she had ever seen.
"It is amazing to think that we saw it just 50 metres away from The Water of Leith visitor centre where there are lots of people.
"We watched it fishing for food and catching and eating fish."
Otters are rarely filmed in the wild in city centres
Iain Ross, a Scottish Natural Heritage (SNH) spokesman, said: "This exciting new video evidence of the presence of otters in the Water of Leith backs up SNH's recent findings that these charming animals have made a remarkable recovery in population terms throughout Scotland.
"Otters are now found in watercourses throughout the country and it is especially cheering to see them thriving in the heart of our major urban areas.
"This shows the improvement in water quality in the Water of Leith is now sustaining a viable food supply for otters and that's great news for people in the city who enjoy seeing Scotland's wildlife up close."
The latest SNH survey, which focused on 1,376 sample sites across the country, discovered positive traces of otter populations at 1,267 locations (92.08%).
The two-year investigation has confirmed the animal is now thriving over the whole of Scotland in both coastal and freshwater sites.
There are now believed to be around 8,000 otters spread across virtually every part of Scotland, including water courses in Aberdeen and the River Clyde.
In particular, all of Scotland's large urban areas now show signs of otters.
In these areas, improvements in water quality have helped create sustainable habitats for otters through increasingly healthy fish stocks and more varied biodiversity.
Otters live mainly on a diet of fish including eels, salmon and trout, but also often eat crabs, frogs and occasionally small mammals and birds.
They live beside the sea or by fresh waters such as rivers, lochs and marshes, but coastal otters must wash their fur regularly in fresh water to maintain its waterproofing quality.
It was made illegal to kill otters in 1981. They are now fully protected by European legislation.
They had previously been hunted for sport, their fur, and because they kill fish