Wildlife and Habitat

Benton Cave Crayfish 512w

Benton Cave Crayfish, photo by John Hollingsworth

  • Gray bat

    Gray bat

    Gray bat (Myotis grisescens)

    The Gray bat is an endangered species. Endangered Species are animals and plants that are in danger of becoming extinct. Threatened species are animals and plants that are likely to become endangered in the foreseeable future. Identifying, protecting, and restoring, endangered and threatened species is the primary objective of the U.S. Fish and Wildlife Service's endangered species program.

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  • Ozark cavefish

    Ozark Cavefish

    Ozark cavefish (Amblyopsis rosea)


    The Ozark cavefish is a threatened species. Threatened species are animals and plants that are likely to become endangered in the foreseeable future. Endangered Species are animals and plants that are in danger of becoming extinct. Identifying, protecting, and restoring, endangered and threatened species is the primary objective of the U.S. Fish and Wildlife Service's endangered species program.

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  • Benton Cave Crayfish

    Benton Cave Crayfish photo

    Benton Cave Crayfish(Cambarus aculabrum)

    Logan Cave is one of only four known habitats for the Benton Cave Crayfish. Cambarus aculabrum is a small, white, crayfish that lives exclusively in caves and ground water systems. It has an overall body length reaching about 48 millimeters (1 .8 inches).

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  • Limestone-solution cave

    Logan Cave is a large limestone-solution cave approximately 1.5 miles in length. The three ecological classification types (tunnel, seepage, and sinkhole) are present in different sections of the cave. The cave’s internal temperature is 55 degrees Fahrenheit. The terrestrial cave environment is extremely stable and such stability is of primary importance to troglobitic organisms that inhabit the cave. However, the aquatic cave environment is not as stable due to the relationship with surface water entering the cave through the recharge area.

    The sinkhole and spring entrances are the only two known entry points. The sinkhole consists of a funnel shaped depression about 50 feet in diameter on a forested hillside and the spring entrance is located on a hillside under an overhanging rock bluff. Upstream from the sinkhole, the cave contains several large seeps which cascade down the walls from the ceiling. These seeps introduce organic matter in the form of fine particulates and dissolved material. These organic materials supply nutrients for many inhabitants of the cave.

    The cave’s passageway is relatively narrow with a low ceiling. In some areas, the ceiling gradually declines leaving only a tiny crawl space. Approximately halfway through the cave is an area where gray bats congregate their maternity colony. This room formed many years ago when large rock plates caved-in.

  • Logan Stream

    Logan Stream is a spring fed stream that extends the entire length of the cave and emerges at the mouth as Logan Spring which has an average water flow of approximately 5 million gallons per day. The spring flows into a natural oxbow lake and then into Osage Creek, a major tributary of the Illinois River. Water clarity in Logan Stream is very high, except after storm events that result in increased flow and decreased clarity. Water quality is high except for seasonal increases in coliform bacteria associated with livestock operations in the recharge zone and traces of pharmaceuticals and other organic wastewater constituents from inadequate septic systems. To ensure success of all species in Logan Cave, water quality needs to remain at a constant high level.

    Logan Stream is divided into three reaches classified by habitat types. The lowermost reach is 365 m long and extends from the cave mouth upstream to the sinkhole. This reach consists of runs and riffles with the substrate being primarily rock and rubble. The middle reach consists of a 230 m long pool that extends from the sinkhole to the next upstream riffle. Rock and silt comprised most of the substrate, with the maximum depth being 3 m. The third reach is 685 m and extends upstream from the pool to point where the cave roof meets the stream. This reach includes pools, riffles, and runs, with gravel, silt, and bedrock substrates.

  • Recharge zone

    The recharge zone for Logan Cave is the surface and groundwater regions that contribute water to Logan Cave stream and spring and is a 7,680 acre area, lying north and east of the cave entrance. The surface streams in the recharge zone are primarily discrete sinking streams that flow through agricultural areas, pasture land and residential areas. Recovery of the species utilizing Logan Cave is directly related to the water quality in Logan Stream which is directly affected by land uses within the recharge zone.

    The recharge zone for Logan Cave is delineated into hazard areas to identify those surface areas which have differing potentials for the introduction of groundwater contaminants into Logan Cave: 1) low hazard, 2) moderate hazard, 3) high hazard, and 4) very high hazard areas; the higher the hazard, the higher in priority for protection of these areas.