Wildlife experts are asking people in Derby to help them spot one of the country's rarest mammals.
Otters almost disappeared in the middle of the 20th century
Derbyshire Wildlife Trust is asking people to help them find out exactly how many otters are around the city.
Wildlife officers say evidence of the creatures has been found both north and south of the River Derwent.
Phillip Precey from the trust said otters virtually disappeared in the middle of the last century, because of pesticides and poor water quality.
He added: "As pesticides are no longer used, the water quality's coming up, the rivers are a lot better now and as the fish come back, so the otters will come back."
Otters are mainly nocturnal, but evidence of their presence can be found via their droppings.
"They look a bit like cigar ash and they smell of jasmine tea, and they're made of fish bones and fish scales - so once seen, never forgotten." Mr Precey said.
Anyone who sees either an otter or their droppings should contact Derbyshire Wildlife Trust.