ELLIOTT ET AL.: THE CAVE FAUNA OF CALIFORNIA 
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The three major threats to cave faunas in California are 1) the massive development of water 
resources driven by the demands of an expanding population and agricultural development, 
2) degradation of the cave environment because of increased visitation by uninformed people, and 
3) destruction of caves by quarrying and land development. 
The scope of development of California’s water resources is phenomenal, involving damming 
of most major and minor rivers, extensive extraction of groundwater, and massive transfers of 
water across the length and breadth of the state (Carle 2009). As a consequence, some caves are 
vulnerable to inundation. For example, the construction of the New Melones Dam in the Sierra 
Nevada inundated approximately 30 known caves, including McLean’s Cave (Elliott 1981b, 
2000b; Anonymous 2009b), a biologically significant cave, which contained four cave-restricted 
species (Table 15). Dewatering of caves, as well as other subterranean aquatic habitats, due to 
depletion of groundwater is also possible. Numerous springs throughout the state have ceased to 
flow as a consequence of declining water tables, with resulting detrimental impacts on resident fau¬ 
nas. 
Quarrying activities in both karst and volcanic rocks also pose a direct threat to caves and their 
faunas. Limestone is in demand for cement, road material, and construction/decorative stone. Cin¬ 
der cones and associated lava flows are also exploited for road material and decorative stone. 
Alabaster Cave in El Dorado County, the type locality and only known site for two troglobites (the 
opilionid Banksula californica and trechine beetle Anillaspis explanata ) has been nearly eliminat¬ 
ed by quarrying, and the remnant was sealed with concrete. The two troglobites have not been 
observed in recent decades, and may be extinct (Briggs 1974 and our data). The population of the 
troglobite Banksula melones in McNamee’s Cave in Tuolumne County apparently was extirpated 
by explosives used in quarrying (Briggs 1974; our data; Bruce Rogers, pers. comm.). The Pisgah 
lava flow in the eastern Mojave Desert contains a significant array of lava caves, estimated at 200- 
300 caves. The fauna has not been extensively documented. The cinder cone was subject to past 
quarrying activities beginning in 1948, although the actual caves are located at some distance from 
the quarry area (Harter 1992b). 
Surface development (urbanization, agriculture) also threaten cave environments. Sealing of 
entrances, pollution (especially of groundwater), and increased disturbance all contribute to 
increased impacts on cave environments and their faunas as a direct consequence of surface devel¬ 
opment. The Santa Cruz Karst is in a highly developed urban area and has been significantly 
impacted. Empire Cave, in that karst region, ranks third in biodiversity among California caves, but 
it has been trashed by numerous visitors for many years. A concrete barrier greatly reduced the 
entrance dimensions with impacts on the fauna (Graham 1967). Although gated in the past, 
attempts to control access have been unsuccessful and significant disturbance continues. 
Improperly designed cave and mine gates of the past were detrimental to fauna. Bats are most 
sensitive to this activity, however other taxa may be impacted from alteration of air flow, nutrient 
inputs, or exclusion. Gate designs have greatly improved in recent decades, and wildlife-friendly 
gates are now the norm. Airflow, nutrient inputs, and movement of small animals are increasingly 
taken into account. For example, by ensuring that the bottom bar of a steel gate is attached to the 
angle-iron columns a small distance above the floor, even small amphibians may come and go 
while excluding humans. Where there is a soil substrate, human intruders are prevented from tun¬ 
neling under the gate by placing an expanded metal mat in a shallow trench below grade and build¬ 
ing the gate on top of it, then backfilling the trench. Authorized visitors may enter via a hidden, 
removable bar with a protected lock. With this design there is little air dam or water dam effect 
(Elliott 2012). Bat Conservation International, an NGO, provides excellent information on the 
topic of cave and mine gating (Fant et al. 2009). Sealing off caves is obviously detrimental and 
