O’SHEA, CRYAN & BOGAN: UNITED STATES BAT SPECIES OF CONCERN 
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Texas : In Big Bend National Park in Texas, Easterla (1973, p.96) described this species to be 
“fairly common”, ranking fourth in relative abundance throughout the park (496 among 4,807 bats 
captured of 18 species at 32 localities, but including 296 captures at roosts; Easterla, 1973). They 
were rarely captured and ranked 13 th in relative abundance (17 captures among 1,978 bats) of 17 
species in a subsequent study during 1996-1998, which emphasized surveys over water in lowland 
habitat at the park; all captures in the latter study were in rocky canyons (Higginbotham and 
Ammerman, 2002). Townsend’s big-eared bats ranked eighth out of 14 species (nine among 542 
individuals) captured by mist net sampling at 108 localities over water in northern Chihuahuan 
desert habitats described as desert scrub, desert grassland, riparian, and juniper roughland at Big 
Bend Ranch State Park, northwest and upstream of the national park, in the Trans-Pecos region of 
Texas; capture records only were in riparian woodland habitat (Yancey, 1997). They were low in 
relative abundance (three captures among 1,329 individuals in 12 species, ranking tenth) captured 
in mist nets set over water at Palo Duro Canyon State Park in the Texas Panhandle, where habitats 
consisted of mesquite (Prosopis glandulosa )-juniper associations, grasses, cacti, and a riparian 
zone of cottonwood {Populus deltoides ) and salt cedar (Tamarix ramosissima) set within sand¬ 
stone, shale, and limestone canyon walls (Riedle and Matlack, 2013). 
Central Rocky Mountains and Western Great Plains: Colorado : Townsend’s big-eared 
bats ranked twelfth (13 captures among 1,996 bats of 15 species) in predominantly pinon-juniper 
woodland habitat at Mesa Verde National Park in southwestern Colorado during 2006 and 2007 
(O’Shea et al., 2011a). In an earlier study at Mesa Verde National Park during 1989-1994, they 
ranked third most abundant (20 bats among 189 individuals in 11 species; Chung-MacCoubrey and 
Bogan, 2003). Differences in relative abundance between the two studies were probably due to 
greater selection of smaller pools of water for netting during the earlier work: small pools were less 
available during the 2006-2007 study but were likely more easily approached for drinking by the 
highly maneuverable Townsend’s big-eared bat than by many other species (O’Shea et al., 2011a). 
This species ranked tenth in abundance among 11 (five out of 546 bats) captured over stock ponds 
during surveys in pinon-juniper woodland at about 2,100 meters elevation in the Uintah Basin of 
Moffat County in northwestern Colorado during 1979-1981 (Freeman, 1984). Townsend’s big- 
eared bats ranked eighth among 10 species (12 captures out of 1,398 individuals) taken in pon- 
derosa pine and Douglas fir forests along the Colorado Front Range in Boulder County (Adams et 
al., 2003) and were the least abundant of nine species in a second survey in the mountains of adja¬ 
cent Larimer County, with one bat captured among 634 individuals (O’Shea et al., 2011b). In 
western Colorado, this species was ranked twelfth of 16 species (seven captured among 899 bats) 
documented at Colorado National Monument and the adjacent Mclnnis Canyons National Conser¬ 
vation Area during netting over small ephemeral pools in deep slickrock canyons within primarily 
pinon-juniper woodland and riparian habitats (Neubaum, 2017). They ranked tenth in abundance 
(43 captures among 1,377 bats of 15 species) in mist-netting surveys at Dinosaur National Monu¬ 
ment in northwestern Colorado and adjacent parts of Utah, at elevations ranging from 1,459 to 
2,263 meters (Bogan and Mollhagen, 2016). 
Utah: In northern Utah, mines and caves used by this species tended to be at lower elevations 
in sagebrush grassland, juniper woodland, and mountain brush vegetation communities; a number 
of other surface habitat variables were measured and contrasted but did not show significant dif¬ 
ferences between occupied and unoccupied sites (Sherwin et al., 2000). At Arch Canyon on the 
Colorado Plateau in southeastern Utah, this was among the least abundant species, with two bats 
captured among 295 individuals of 15 species taken at elevations ranging from 1,474 to 1,707 
meters (Mollhagen and Bogan, 2016). Similarly, they ranked tenth of 15 species in relative abun¬ 
dance (16 captures among 572 individuals) in the Henry Mountains of southeastern Utah, where 
