Experts checked a number of places back in 1977, and this year when they went back, they found that otters had been living in lots more of them than they were.

Cleaner water, more fish living in rivers and better care being taken of riverbanks are all things that might have helped.

There used to be loads of otters living here, but during the 1950s and 60s many of them died out, and some were hunted until a ban in 1978.

Roads are a big problem

Water companies have been helping out by building dens for them to live in and making the water they live in much cleaner.

Some have also worked on special projects that help the otters stay away from roads, which are the reason behind lots of otter deaths.