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PROCEEDINGS OF THE CALIFORNIA ACADEMY OF SCIENCES 
Series 4, Volume 64, Supplement 1 
apparently escaped the glaciations of the higher elevation caves in that area, and it is regionally 
important in the western U.S.A. despite its modest size. 
Table 18 is the species list for Clough Cave. The cave has a large list of micropredators, includ¬ 
ing 15 spiders, a harvestman, a schizomid, 3 pseudoscorpions, 2 scorpions, 2 centipedes, 3 beetles, 
and perhaps other arthropods. The detritivores include 1 mite, 3 collembolans, 6 millipedes, a 
bristletail, a silverfish, a japygid, 2 beetles, 2 flies, 2 hemipterans, 2 psocids, and a terrestrial iso¬ 
pod. Vertebrates include raccoon, 4 bats, a rodent, and a snake. This is amazing diversity, especially 
as there are no aquatic species or crickets. Other food inputs to Clough Cave include extensive tree 
roots, animal feces, fungi, pack rats, raccoons, bats, and small arthropods. The roots in Clough 
grow into the cave from the parallel canyon, supporting an associated fauna such as collembolans, 
planthoppers (Figs. 97-101), and arachnids. Many California caves have extensive root systems. 
Clough Cave was the site of an intensive ecological study involving five surveys of terrestrial 
fauna between May and December 2010 (Tobin et al. 2013). The cave was divided into six quadrats 
and temperature was continuously logged in each; humidity was logged at the entrance and in the 
deep cave. With increasing distance from the entrance, temperature changes were increasingly 
attenuated and lagged relative to surface temperature changes. The temperature ranged from 
2-28°C at the entrance and 12-18°C in the cave. Quadrat 6, at the far, upper end of the cave, was 
relatively stable with a range of 15.5-17.2°C over the study (May to December 2010). Linear 
regressions were created to determine the relationship between measured environmental variables 
and diversity for cavemicoles (troglobites and troglophiles) and trogloxenes cave-wide and in the 
transition zone. Diversity for cavemicoles and trogloxenes peaked in the entrance and deep cave 
zones, respectively. Quadrat, date, 2-week antecedent temperature average, 2-week antecedent 
temperature range, and trogloxene abundance explained 76% of cavemicole diversity variability as 
measured by the Shannon-Weaver index, H\ Quadrat explained 55% of trogloxene diversity vari¬ 
ability. In the transition zone, trogloxene abundance explained 26% of cavemicole variability and 
2-week antecedent temperature and 2-week antecedent temperature range explained 40% of 
trogloxene variability. In the transition zone, trogloxene diversity was inversely related to 2-week 
antecedent temperature average and 2-week antecedent temperature range, suggesting that species 
were moving into the transition zone when temperature was most stable. In a canonical correspon¬ 
dence analysis of cavemicole distribution data and environmental variables, 35% of variation in 
species-specific distributions was attributable to quadrat, and nonsignificant percentages were 
explained by date and environmental variables. 
Samwel Cave. A map of Samwel Cave (Fig. 115), Shasta County, Shasta National Forest, Kla¬ 
math Mountains Region, and Table 19 detail its structure and fauna. With 44 species, 11 troglobites 
(including 4 single-site endemics), and a site endemism score of 5.92, the cave ranks second for B, 
and first for B 2 . It has the most single-site endemics of any California cave, probably because of 
the isolation of the Shasta Karst and because it has received extensive study. Samwel has 8 spiders 
with 4 troglobites, 2 pseudoscorpions (1 troglobite), 2 scorpions (including the only troglobitic 
scorpion in the state), 4 collembolans, 5 millipedes (3 troglobites), 1 japygid (troglobite), 3 beetles, 
3 dipterans, a moth, a new species of cricket, a psocid, a terrestrial isopod (troglobite), a salaman¬ 
der, a bat, 7 snails, and has had a porcupine and a puma. Samwel Cave has been studied by many 
scientists since 1903, yielding interesting late Pleistocene fossils (Feranec et al. 2007) and new 
species of arthropods (see History section). It sits at 438 m elevation, is 300 m long and 30 m deep 
with a significant drop to the bottom. A tree grows at the entrance and roots are prominent in sev¬ 
eral parts of the cave. The roots support many arthropods, including Titiotus spiders, as observed 
by Darrell Ubick. A recent paleontological excavation in the top level of the cave (Putnam Hall) 
found roots down to 1.1 m below the floor level (Jessica Blois, pers. comm.). Unfortunately, 
