Cave Biology: the observations of a geologist!

My interest in cave biology began in Ogof Draenen in the days when it was just our ‘club dig’. I took part in a couple of surveying trips and as anyone who has visited Ogof Draenen will testify, the cave was small and cramped and in the inevitable hanging around that occurs in these situations, I nosed into every nook and cranny. Being a geologist at heart, I took a keen interest in the limestone about me. The thinly bedded limestones of the entrance are part of the Llanelli Formation with delicately coloured inter-bedded green clays. Tracing one of these green clays one Thursday evening as I lay in what was then known as the ‘long crawl’ to me, I spotted a caddis fly and near by a beautiful orange herald moth with a distinctive ragged edge to its wings. That was it, I was hooked! Armed with my trusty copy of Phil Chapmans Cave Biology book, my collection of observations grew slowly to include fungus gnats, a fresh water shrimp and even a dozzy dung fly. Tim Long found me a fox femur from the eroding gravel in the entrance and we even found parts of a very young badger skeleton and that was all while the cave was just tens of metres long!

Bats have formed a large part of the observations of cave biology in Ogof Draenen and are largely Lesser Horseshoes. The present day numbers of bats in the cave are relatively low but this has obviously not always been the case with huge piles of guano see in Raiders Passage as well as scatterings of fine guano in many passages and of course the exquisitely delicate skeletons dotted about the cave. The evidence suggested that at some time in the past, the cave was much more heavily used by bats but not today.

It is important that we develop more of an understanding of the bats in the cave, their positions with in the cave, how much they move about through time so that we can minimise our impact on them. Bats are protected by law and it is an offence to interfere with them. They are at their most vulnerable during the cold winter months when they roost. Disturbance causes them to wake when there is no food (midges and other flying insects) available for them and they will inevitably die. Any observations of bats within the cave would obviously be gratefully appreciated.

I have heard tantalising information about hyena teeth and brown bear bones that have been removed from the cave and I would love to hear more about these. In general, it is advisable to leave any specimens within the cave. The conditions in the cave are very consistent and leaving objects in the cave is the best way of preserving them. If you find anything of interest, the best thing to do would be to place tape around it. If in the rare event that material needs to be removed because it is in danger of being destroyed, please let me know as it would be great to have all such material in one place. I suggest the National Museum and Galleries of Wales as they are experienced in looking after cave material and also local to the cave.

Below is a list of the various species found in Ogof Draenen but another interesting (and I suppose this is the geologist in the speaking now!), are the fossils in the limestone itself. Within the creamy coloured Gilwern Oolite are black fossils, standing proud from the rock as they are relatively harder than the surrounding limestone. These are small fragments of fish bone, teeth and plates as well as the impressive spines from their fins. These spines are often horseshoe shaped in sections and have beautiful ornamentation.

Over the years I have tried to learn as much as I can about the amazing creatures that live in caves and its been a hobby that has given me much enjoyment. The more you learn about the natural inhabitants of the cave and their fragile environment, you increasingly feel a need to try and protect them. A big thank you to everyone that has contributed records and please keep them coming. Don’t be daunted by identifying things, a note that cave life has been seen in an area is valuable and much appreciated.

Thank You

Rhian Hicks
Biological Recorder

Acicula fusca
Bat guano
Bat Skeletons
Black fungus gnat
Caddis Fly (undet)
Carychium minimum
Cave Hyaena
Clausilia bidentata
Discus rotundatus
Ena obscura
Gammarus pulex
Heleomyza serrata
Larvae (undet)
Limonia nebeculosa
Lithobius sp
Myotis nattereri
Niphargus fontanus
Oxychilus cellarius
Proasellus cavaticus
Pupilla muscorum
Rana temporaria
Rhinolophus hipposideros
shrimp (undet)
Snake Millipede
Speleolepta leptogater
Stenophylax permistus
Trichia hispida
Trichia striolata
Vitrea contracta