Otter numbers are on the increase in Bedfordshire because river habitats are improving, a study has shown.
Otters have made a comeback across Bedfordshire
The study, by the Greensand Trust on behalf of Bedfordshire County Council, revealed better water quality.
The presence of otters reflects the overall health of their habitat and the rare animals are often used as indicators of river condition.
In the 1980s otters were thought to be extinct, but the new study has found a big increase in otter droppings.
A Greensand Trust spokesman said: "We almost suffered the extinction of otters in East Anglia in the 1970s.
"This was due to pesticides getting into river systems and because otters are at the top of the food chain.
"There was a massive mortality in the number of otters but the Otter Trust, based in Norfolk, was instrumental in re-introducing them into rivers in East Anglia.
"The particular pollution responsible for the otters virtual extinction is not in the river systems any more."