Water voles live in burrows excavated within the banks of rivers, ditches, ponds, and streams. Their burrows are normally located adjacent to slow moving, calm water which they seem to prefer. They also live in reed beds where they will weave ball shaped nests above ground if no suitable banks exist in which to burrow.
They are expert swimmers and divers. They do not usually live in large groups. Adult water voles each have their own territories, which they mark with faecal latrines located either near the nest, burrow and favoured water's edge platforms where voles leave or enter the water. Latrines are known to be a good survey indicator of this species, and can be used to gauge abundance of animals. They also scent-mark by using a secretion from their bodies (a flank gland), however this is not normally detectable during a field survey. They may attack if their territory is invaded by another water vole.
Ecologists have discovered that normally vegetarian water voles living in Wiltshire have started eating frogs' legs and discarding the bodies. It has been speculated that this is to make up for a protein deficiency in the voles' diet.
Text and photographs courtesy of Wikipedia.