WHEN is a rat not a rat? When it is a water vole! Those of us who live near towns know the brown rat is one of our most dangerous pests. They deserve to be regarded as vermin.

The water vole (Ratty in Wind in the Willows) is a harmless vegetarian but is sadly becoming rarer and is now a threatened species.

An adult brown rat weighs around 500gms and has a much larger and longer body than the water vole. It also has a pointed muzzle, a naked tail, more pronounced ears and a tail about the same length as the body and head together.

The water vole, on the other hand, weighs between 200 and 400 gms. It has a shorter, rounder body, a blunt muzzle, a tail covered in fur, short ears and a very much shorter tail.