Westerham Mines

Also within

Kent County Kent Downs Scenic Area

Condition (Natural England)

Habitats

Bracken scrub

Geology & landscape

Rock Type: Greensand

Birds & fish recorded

Birds

Description

Description The principal interest of this site is the use of its abandoned ragstone mines by a variety of hibernating bats. The surrounding area is chiefly mixed secondary woodland on former heathland, with pockets of remnant heath. With the increasing scarcity of bats in south east England and the continued loss of the few suitable hibernacula remaining available to them, these mines represent an important winter refuge for bats in the county. Five species have been recorded hibernating here, whiskered bat Myotis mystacinus, Brandt's bat M. brandti, Daubenton' bat M. daubentoni, Natterer's bat M. nattereri and long eared bat Plecotus auritus. The number of bats using the mines declined from the 1950s onwards, largely because of disturbance, but the fitting of grilles allowing access for bats, but not humans and devices to maintain the air flow through the mines is thought to have led to an increase in numbers in recent years. However, it is very difficult to locate all the bats using the tunnels and different species use them at different times during the winter. Thus it is extremely hard to estimate the true numbers using the mines. There is also evidence that some use is made of the mines by bats in summer. A rich insect fauna exists in and around the tunnels, flies Diptera being particularly well represented and some moths also hibernate in the mines. The mixed woodland around the old mines is typical of that which now covers much former heathland on the Lower Greensand in Kent. Oaks Quercus petraea and Quercus robur, birch Betula sp., bracken Pteridium aquilinum and Scot's pine Pinus sylvestris dominate the vegetation, but remnants of former heathland, including ling Calluna vulgaris, bilberry Vaccinium myrtillus and heath bedstraw Galium saxatile, occur locally. The area has supported a rich heathland breeding bird community, including nightjar.

Species mentioned

Insects to look out for

These moths, butterflies and beetles are known to feed on plants recorded at this site, and carry a notable UK conservation status — but a host-plant being present doesn't mean the insect has actually been recorded here. Treat this as "worth watching for," not a confirmed sighting.

Host-plant data: Cook et al. (2025), Traits data for the butterflies and macro-moths of Great Britain and Ireland, 2024, UK Centre for Ecology & Hydrology / Butterfly Conservation; and Padovani et al. (2020), Database of Insects and their Food Plants (DBIF), UK Centre for Ecology & Hydrology (both Open Government Licence). Contains data supplied by UK Centre for Ecology & Hydrology.

Plant communities