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PROCEEDINGS OF THE CALIFORNIA ACADEMY OF SCIENCES 
Series 4, Volume 65, Supplement I 
found call-based evidence at 34 sites in 10 areas, supporting the hypothesis that spotted bats are 
uncommon compared to other species (Fenton et al., 1987). Many bat faunal surveys within the 
general distribution of the spotted bat fail to document their presence through captures (see below 
for examples), although they can be detected in more localized regions using acoustic survey tech¬ 
niques (for example, Navo et al., 1992; Storz, 1995; Kuenzi and Morrison, 1998; Pierson and 
Rainey, 1998b; Rodhouse et al., 2005). 
Pacific Northwest and Northern Rocky Mountains: Published bat faunal surveys using mist 
nets over water in Oregon, Washington, and Idaho have not reported captures of spotted bats at the 
locations sampled (Whitaker et al., 1981; Thomas, 1988; Perimeter, 1996; Baker and Lacki, 2004; 
Lacki et al., 2007), although their presence in these states is otherwise documented (Handley, 1959; 
Verts and Carraway, 1998; Hayes and Wiles, 2013). Spotted bats were the least abundant of nine 
species (two of 231 individuals) of bats captured over water in the Pryor Mountains of south-cen¬ 
tral Montana (Worthington, 1991). 
One spotted bat was captured over water in the semi-arid Okanagan Valley of southern British 
Columbia, where the species ranked as least abundant of 12 species documented through capture 
of 958 individuals (Woodsworth, 1981). None were captured in an earlier survey in the same 
region, where an additional 351 bats of nine species were captured (Fenton et al., 1980). 
California and Nevada: In the Sierra Nevada mountain range of California, the spotted bat 
ranked eleventh of 17 species (seven individuals among 390 bats) captured in mist nets at 19 sites 
during 1993-1999 (Pierson et al., 2001). None were captured among 1,398 individuals of 15 
species taken in mist nets set over water during four summers in the upper Sacramento River area 
of northern California (Pierson et al., 1996b), and none were captured during mist-netting surveys 
in Whiskeytown National Recreation Area in Shasta County, California, where 47 sites between 
256 and 1,899 meters elevation were sampled in a variety of habitats and yielded 403 bats of 10 
species (Duff and Morrell, 2007). 
In south-central Nevada, five of these bats were taken among 2,099 (0.2%) bats of 13 species 
captured in mist nets, ranking twelfth in relative abundance, and were netted only in Great Basin 
Desert habitat (Hall, 2000); three of these bats were captured among about 2,000 bats of 14 species 
netted over water in the White and Inyo Mountain ranges of Nevada and California (Szewczak et 
al., 1998). Spotted bats ranked tenth (three captured among 299 bats of 11 species) in mist-netting 
surveys over water in west-central Nevada in habitats categorized as desert shrub and pinon-juniper 
woodland zones (Kuenzi et al., 1999). In a comparative study of differential use of habitat types 
within riparian areas in the Mojave Desert of southern Nevada, acoustic activity of these bats over 
open riparian marsh was greater than any other species measured; they also were active over 
mesquite bosque but not riparian woodland or riparian shrubland (Williams et al., 2006). 
Southwestern U.S.: Arizona : Spotted bats were fourteenth in abundance (two captures among 
3,458 individuals of 17 species) in a summary of mist-netting records over water in Mohave Coun¬ 
ty of western Arizona (Cockrum et al., 1996), where authors remarked that their high maneuver¬ 
ability and habits of roosting in high cliffs reduce their susceptibility to capture in mist nets. They 
ranked ninth in abundance among 17 species of bats (18 captured of 1,171 total bats netted) taken 
over water mostly in ponderosa pine and pinon-juniper habitats of the Arizona Strip in northwest¬ 
ern Arizona (Herder, 1998). They constituted 4% (47 captured) of about 1,175 individuals of mul¬ 
tiple species sampled over water at multiple sites in extreme northern Arizona (Chambers et al., 
2011). None were taken in surveys over water in ponderosa pine and mixed ponderosa pine-Gam- 
bel oak forest of north-central Arizona, where 15 other species and 1,673 individuals were captured 
(Morrell et al., 1999). 
New Mexico : Spotted bats ranked seventeenth among 20 species captured (a total of seven out 
