Since then they have been monitored by the Wildlife Trust and Mammal Group. They have probably bred in Hertfordshire and currently mainly use the lower Lea and the Stort. A secretive, nocturnal semi-aquatic carnivore.
Fish are their most important food.
They will take coarse fish, eels and salmonids depending on what is present. A good indication of the presence of otters is the discovery of their spraints. They can travel over large areas of river habitat. They can live up to 10 years although few survive over 6 years. Otters are highly selective in their choice of habitat.