During our 2003/4- and 2005-expeditions, extensive collections of the cave fauna were undertaken . Specimens of arthropods, molluscs and other lower animals were collected by hand and preserved in 70% alcohol. An effort was made to get a sample as representative as possible for each cave. Skulls of bats and other mammals were collected as well. Of living mammals, reptiles and amphibians, only photographic evidence was taken, whenever possible.

The identification of fauna collections is a slow and arduous process. A typical collection will contain anything from mammals down to worms. Specialist knowledge is required for identification even beyond the level of orders. Specialists, especially those who are familiar with groups from the tropics, are few and usually overburdened with work. If you are lucky enough to find one willing to take a look at a specific part of your collection, it still may take years until you get results. Descriptions of new species, which are almost inevitably found in every extensive collection of tropical cave fauna, may require major taxonomic reviews and thus take even longer. Therefore, in order to publish this expedition report in due time, the results of our biospeleological research will be restricted to summary data and a few anecdotal observations.

Animals typically encountered in Lao caves are:

• cave crickets. They are commonly found on the walls and on the ground of almost every cave. No identification has been obtained so far. They belong to the family Rhaphidophoridae, probably to the genus Diestrammena.
• large assemblies of green grasshoppers. They were found in a few caves, usually in cracks in dark spots near the entrance. Their bright colour typifies them as animals from outside sheltering in the caves.
• mass assemblies of opiliones. They are usually found in some dark crack near the entrance and may number from a few dozen to several hundreds or even thousands. They are not identified yet, nor has any report of this behaviour been seen so far.
• an assortment of different spiders
• large huntsman spiders of the family Sparassidae. It is not yet clear whether these are the same species as the giant Heteropoda maxima from Khammouane province, described by Jäger (2001).
• whip scorpions of rather large size, which belong to the genus Typopeltis (J. Haupt, pers. comm.). The species couldn't be acertained, since both specimens were juveniles. They may or may not be the same as the newly described Typopeltis maximus (Haupt 2004).
• large longlegged centipedes, probably of the genus Thereuopoda. They are currently described as a new species (Würmli, pers, comm.)
• on or near guano patches an abundance of millipedes, at least two different species.
• on the walls notably pale isopods.
• close to the entrance on the wall a large Noctuid moth was often seen. It has dark wings with eye-spots and was tentatively identified as Erebus macrops (W. Nässig, Forschungsinstitut & Museum Senckenberg)
• rats. A rather large and quite beautiful looking rat was observed in a lot of caves.

All in all, during the 2003/2004-expedition, 204 animals were collected in 15 different caves. 17 of them mammals, 14 of them bats, 105 insects, 18 crustaceans, 43 arachnids, 16 myriapoda, 4 snails and 1 worm.

During the 2005 expedition, 298 animals were collected in 5 different caves, comprising 3 bat skulls, 85 arachnids, 49 crustaceans, 60 insects, 86 myriapoda, 13 snails and 2 worms.