On 23 November 2011 I entered the upstream entrance of Twin Cave to do a snapshot assessment of the condition of the cave community. The cave entrance is in the floor of a sinkhole and allows rapid access to the main stream passage of the Donaldson (Shawnee) Cave System after climbing down a breakdown slope.

Several areas of raccoon scats were present along the breakdown slope. Troglobitic invertebrates present were the Subterranean sheet-web spider Phanetta subterranea, Bollman's cave millipede Conotyla bollmani, an undescribed (new to science) species of the cave dipluran Litocampa, and the Cave dung fly Spelobia tenebrarum. Along the breakdown slope and adjacent to the cave stream several more of the Subterranean sheet-web spiders were seen, along with one individual of the slightly more robust, straw-colored troglobitic Cavernicolous sheet-web spider Porrhomma cavernicola. The cave stream was high and flowing very briskly from rain during the previous two days. Visibility in the water was limited due to the turbidity caused by the stream flooding. A few slabs of breakdown were pulled from the water and each contained several of the cave isopod Caecidotea stygia.

Vertebrates noted in the cave were a Slimy salamander Plethodon glutinosis, a Tri-colored bat Perimyotis subflavus, and the droppings of the Raccoon Procyon lotor.

I remained in the cave for about 30 minutes. The terrestrial fauna noted was typical for a cave in the Mitchell Plain, although the presence of the dipluran Litocampa was of particular significance as I believe it was previously unknown from this system. The presence of the cave isopod Caecidotea stygia was typical of healthy cave streams in this area. No biofilms were noted under the stones nor any organisms consistent with nutrient enrichment. Based on this snapshot, the cave community appeared intact.

Although a comprehensive bioinventory has never been conducted, fifteen species of troglobites are known from the Donaldson (Shawnee) Cave System. Several species of karst invertebrates undoubtedly remain undiscovered as no species of, e.g., springtails have been reported, although they are undoubtedly present.

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