The three types of cave dweller.........
TROGLOBITES: Truly cave-adapted species which live permanently underground and cannot survive outside the cave environment.
TROGLOPHILES: Cave-dwelling species that may complete their life cycle in a cave, but can also survive outside the cave environment.
TROGLOXENES: Species which live close to caves or cave entrances, such as cave swallows. Although they use caves, they cannot complete their life cycle in caves only. Aquatic trogloxenes are known as stygoxenes.



Of the 16 species of UK bat, six use underground sites in North Wales: Daubenton’s, lesser horseshoe, brown long-eared, Natterer’s, Brandt’s and whiskered bats.

In addition, Dr Henry Schofield, conservation programme manager for The Vincent Wildlife Trust states that "Greater horseshoe bats are now recorded as summer residents in North Wales and it seems only a matter of time before breeding colonies are found in the area".

North Wales has 10,000 lesser horseshoe bats of the UKs total population of 17,000, despite being their most northerly stronghold. Although rare or non-existent in many UK areas, lesser horseshoes are frequently seen underground in this area where their population has been increasing since 1999. They hang from the roof in caves and mines and are easily seen, whereas the other five species tend to hide in crevices or under boulders.

Bats live for up to 15 years and hibernate between October and April, when their body temperature can drop to as little as 2 degrees centigrade and their heart beats just 10 times a minute. If disturbed during hibernation, they wake slowly. Over half an hour their body temperature rises from an average of around 10C. to 20C. and their pulse increases from about 20 to 600 beats a minute. This uses large reserves of energy, stored as fats, and is energy they struggle to replenish. Hence the need to avoid disturbing them with noise or lights.

All UK bats are protected by UK and EU legislation on the grounds that many are reported to be declining in numbers, some being classed as being 'endangered'.

The monitoring of species, numbers and locations is carried out by the amateur sector; by Clwyd Bat Group and Sam Dyer Ecology, both being answerable to Natural Resources Wales (NRW). Data on bats however, is not released to the public, it being classed as 'sensitive'. An annual report is available to the public however, which does provide a snapshot of species numbers and distribution (see Sources below).

Several underground sites in North Wales have been fitted with 'bat grilles' by NRW to minimise disturbance, although it should be noted that even authorised monitoring by licenced inspectors can have a damaging effect on numbers: "In Britain, Stebbings (1965) has shown that 5 visits per winter were sufficient to reduce the number of bats by 50%, even though they were not subject to excessive disturbance. When interference, ringing especially, was minimised, by reducing visits to 1 per winter, the bat population increased over a period of 4 years." (Yaldon & Morris [1975] see Sources below).

Bat threat to future caving?

It has long been NRW policy that caver access to sites containing bats be restricted to their waking months between April and September. In recent years however, a new EU Directive states that no access should be permitted to a cave with bats at any time of the year. This has already been shown to affect archaeological work in North Wales, where Clwyd Powys Archaeological Trust had to abandon their work at more than one cave site during the summer months. Knowing how rigidly NRW adhere to regulations, it may only be a matter of time before caving is outlawed. This may seem alarmist, but NRW have consistently been unwilling to engage with local caving clubs, on any subject, and this EU legislation could provide them with a convenient means of exclusion.

Clwyd Bat Group

Although the main local organisation is Clwyd Bat Group, they cannot be regarded as a helpful organisation. The only contact provided by their website is by email, but enquiries using this are regularly ignored. To quote their Mike Castle a few years ago "I don't have time to answer emails". Sadly the group continues to ignore bona fide enquires via email (in 2019).


Yaldon & Morris (1975): "The Lives of Bats" is an excellent book on the topic, available second hand for around £8:

Although Clwyd Bat Group do not provide the public with data, the Joint Nature Conservation Committee (JNCC) and Bat Conservation Trust are happy to share their "National Bat Monitoring Programme - Annual Report 2018" online:

Cambrian Caving Council provide an excellent guide to UK bats (from which much of the above information was taken):

An early North Wales bat survey was carried out between the years 1960 and 1967 by Lynx Cave excavator John Denton Blore. Although his detailed account is currently only in hard copy, if a few people are interested, the writer will digitise the report. Get in touch at:


Other life forms

Microbes, bacteria etc

During the exploration of caves, the only life forms normally encountered by cavers in North Wales are bats, cave threshold spiders (Meta Menardi) and insects carried in by natural ventilation. Look carefully however, and more will be revealed. Cave life can include bacteria, fungi, plants, algae, protozoans, sponges, eels, segmented earthworms, slugs, snails and crustacea.
Mines occasionally exhibit b acterial growths in the form of hanging jelly-like microbial biofilms known by UK cavers since the 1960s as 'snottites'. Strains may be related to Sulfobacillus or Acidimicrobium? A fine example was seen in the Halkyn Tunnel in the 1970s when a forest of twelve inch long draperies covered an area of about eight square feet.

Microscopic bacteria or microbes exist in abundance in caves and mines and may have an important role in the formation of 'moonmilk', travertine and tufa deposits.
Microbial involvement can often be seen on rusting ironwork in mines where iron, shell-like forms can appear to be 'growing' (see image below). They visually mimic bi-valve molluscs and are formed by chemical action influenced by microbes.
Examples two inches long have been seen in several slate mines in North Wales.

Shell-like ferrous growths on iron bar in north Wales Photo: Vanoord

Chemoautotrophs: Some bacteria found in caves are self-feeding 'bugs' capable of converting inorganic matter into organic, and are thought to represent the earliest life-forms on earth. They are specialised micro-organisms that gain cellular energy from the chemical oxidisation of rich inorganic compounds, such as hydrogen, reduced iron or hydrogen sulphide.

Chemolithoautotrophs: A form of bacteria capable of 'eating' limestone and enlarging caves (i.e. Movile Cave, Romania and Lechuguilla in the US), although it hasn't been identified in north Wales.

Although these life forms are rich areas of study, virtually no research on the topic took place in the caves and mines of north Wales until recently. It is understood that specialists from the University of Bangor are currently examining a number of mine sites in the area.

When on your next caving trip, why not spend a little time looking for life-forms of any kind and if possible, take close-up photos or collect samples to have identified and recorded.

Photo taken recently by Ian Adams in Afon Meirchion Cave, Cefn. The species has not yet been identified.....

The troglobite cave shrimp Niphargus fontanus in Ogof Ffynnon Ddu 1, south Wales.

Cambrian Caving Council website has a website dedicated to life in caves:
BCRA page on cave biology at:
Website specialising in cave shrimps at:
To view a large selection of cave life photos:
For an interesting book on cave-eating nanobacteria & other extremophiles:
Clwyd Bat Group: Contact Karl Martin at
Use 'The Bats of Britain' to identify a species:

Two factsheets are available from BCA as downloadable PDFs: 'White Nose Syndrome in Europe' and 'Bats Underground':

Please treat this page as your own and feel free to send in any cave life photos or information. All will be credited

The common cave threshold spider, Meta Menardi

Although not normally cave dwelling, this specimen was found inside the entrance to Coppy Farm Cave No. 3.
It is one of the Opiliones or Harvestmen, easily recognisable by the way that at rest it holds its leg out at right angles to the body and that the pedipalps are forked.
Thus its species is Dicranopalus ramous, which is actually a recent invader from Morocco.
(With thanks to Karl Martin for this information).

Water-borne fungus feeding on minerals (?) or organic materials carried by waters from Halkyn Mountain cave system
Photo: Glen Walker

Lesser horseshoe bat in Cefn Cave

Fungus initially growing from the abandoned tea-urn, searching for nutrients (in Halkyn Mines at Hendre near Mold)
The table was entirely devoured by the fungus within about two years
Photo: Barry Johnston