Otters have been successfully reintroduced to a Suffolk river after nearly 40 years, conservationists said.
During the 1960s and 1970s, pesticide pollution in the River Stour nearly wiped out the mammals.
Recently, Stour Valley Project put a small number of the mammals back into the river and built 20 holts - man-made hideaways - to track their survival.
Peter Ennis, from the project, said one of the holts was now in permanent use and the otters were also breeding.
The project's landscape and biodiversity officer, Mr Ennis, said he was optimistic that more holts would be used in the future.
"There will never be huge numbers of otters because being top predators they need about 20 miles of river to hunt in and they are sometimes killed crossing roads," he added.
"They are by no means secure but things are looking good. It's fantastic news."
Stour Valley Projects also improves habitats for threatened species such as the barn owl, dormouse, water vole and native black poplar.