Badgers use a complex system of underground tunnels leading to multiple entrance holes, the number of which has no bearing on how many animals actually use the sett.If you find a badger sett, count the number of entrance holes that are well used. You can tell this if they have freshly dug earth leading from the inside of the hole to the outside. Also, see if you can find piles of bedding which have been left out by the badgers to dry.
Rabbit
A rabbit's home is similar to a badger's, with a multiple entrance hole system called a warren. However some rabbits live on the surface, hiding in thick bramble in areas where there is little risk of predation. Fox
Foxes make their dens almost anywhere. In urban areas they turn up in the most unlikely places, such as underneath portable dwellings or discarded builders' rubble.
The traditional fox den is usually a solitary entrance hole that may originally have been made by a badger. A good way to tell if a fox is at home is to smell the air around the entrance hole. The harsh musty smell of a fox is often overpowering. It's not unusual for foxes to share a badger's sett, so don't be surprised if you see both species emerging from the same hole.
Grey squirrels live in dreys that look superficially like birds' nests, built as they are from materials such as sticks and moss. Squirrel dreys are usually found close to the trunk of the tree. They can be found in holes in trees or in large nesting boxes. In urban areas squirrels sometimes build their dreys in the lofts of houses.
Otter
Foxes make their dens almost anywhere. In urban areas they turn up in the most unlikely places, such as underneath portable dwellings or discarded builders' rubble.
The traditional fox den is usually a solitary entrance hole that may originally have been made by a badger. A good way to tell if a fox is at home is to smell the air around the entrance hole. The harsh musty smell of a fox is often overpowering. It's not unusual for foxes to share a badger's sett, so don't be surprised if you see both species emerging from the same hole.
Grey squirrel
Grey squirrels live in dreys that look superficially like birds' nests, built as they are from materials such as sticks and moss. Squirrel dreys are usually found close to the trunk of the tree. They can be found in holes in trees or in large nesting boxes. In urban areas squirrels sometimes build their dreys in the lofts of houses. Otter
Otters living close to and in the water make their homes in the banks of rivers. They are called holts, and may be a hole in a bank or at the base of an overhanging tree. 
They are often found where the roots of a tree break the surface of the ground as this helps to keep them secure. Where overhanging trees are absent, man-made otter holts can really benefit this species.
They are often found where the roots of a tree break the surface of the ground as this helps to keep them secure. Where overhanging trees are absent, man-made otter holts can really benefit this species. Water vole
Water voles also make their homes in the banks of waterways. Voles prefer to construct small entrance holes where there is thick vegetation but where the hole can easily be seen from the opposite bank to enable them to swim for cover if threatened. 
Find out more about water voles from Chris Sperring's video diary.
Find out more about water voles from Chris Sperring's video diary.
