She said: “Of the 13 different species of otter around the world only one is found in Europe – the Eurasian Otter.
“These nocturnal mammals have become a flagship species for conservation after rapid declines in the 1950s saw them restricted to just Wales, Scotland, the West country, and parts of Northern England.
“The ban of harmful pesticides, the cleaning up of the waterways, and legal protection has since helped them expand across most of mainland Britain.
“They also appear to be expanding back into our city centres.”
Otters are fully protected in the UK under the Wildlife and Countryside Act (1981) and it is illegal to disturb them.
They are also a priority species under the UK Post-2010 Biodiversity Framework, according to the Mammal Society charity.