Amphibians require a humid environment, so hibernacula for
them are best located close to water. A well-drained rockery near
to a pond would be ideal.
To build a hibernaculum for amphibians, mix plenty of coarse
rubble with leaf mould and rough pieces of wood. If you are
building a new pond, you can make a hibernaculum with the
soil that you removed to create the pond.
Line the bottom of the hole with brick rubble, and then fill with
soil (excavated from the pond, if you are building one), leaf
litter, loose rubble and wood. Cap it off with brick rubble
interspersed with large pieces of concrete to create gaps that
will allow amphibians into the mound.
Cover this rubble cap with a thin layer of soil and woody
brash, taking care not to block off any gaps.