44 
PROCEEDINGS OF THE CALIFORNIA ACADEMY OF SCIENCES 
Series 4, Volume 65, Supplement I 
habitats and elevations of capture sites where this species was taken ranged from 1,295 to 2,396 
meters (Mollhagen and Bogan, 1997). 
Wyoming : Townsend’s big-eared bats ranked tenth of 12 species in relative abundance (four 
captured among about 370 individuals) documented by mist netting in lower elevation basin and 
foothills habitat during 2012 in the south-central part of Wyoming (Abemethy et al., 2013). They 
were not documented among 246 bats of six species captured in mist net surveys over streams and 
beaver ponds in and near the Medicine Bow National Forest in southern Wyoming, at elevations 
ranging from 2,133 to 2,896 meters and in habitats encompassing lodgepole pine (Pinus contorta ) 
and spruce-fir forests (Graver, 2002). 
South Dakota :. This was the third most common species in sampling at Badlands National 
Park in South Dakota, with 43 captured among 405 bats of nine species (Bogan et ah, 1996; but 
see also Famey and Jones, 1980, where they were found to be least abundant in the same park). 
Townsend’s big-eared bats were not documented among seven species and 1,197 individuals of 
bats captured during warm seasons in ponderosa pine-dominated habitat in the Black Hills of South 
Dakota (Cryan et ah, 2000), where hundreds hibernate during winter in nearby Jewel Cave (Choate 
and Anderson, 1997). Similarly, just one was captured among 209 individuals of nine species in 
mist nets set over water during summer 1989 near Jewel Cave (Choate and Anderson, 1997), but a 
maternity colony at the southern periphery of the Black Hills was found through re-visitation of 
several low-elevation sites where disparate records of reproductive females had been previously 
reported (Cryan, 1997). 
Foraging and Dietary Analysis. — Foraging habitat use in this species is likely to be vari¬ 
able. Acoustic sampling in the western hemlock forest zone of the Cascade Mountains in Wash¬ 
ington found that Townsend’s big-eared bats did not use mature stands but were detected most 
often in clearcuts (both habitats had lower indices of use for this species than for other species of 
bats; Erickson and West, 1996). Light-tagged Townsend’s big-eared bats observed in western Okla¬ 
homa shortly after emergence foraged closer to canyon walls and lower to the ground than other 
local species of bats, sometimes foraging within patches of streamside vegetation, and occasional¬ 
ly stopping to rest on rock faces (Caire et al., 1984). Limited observation by telemetry in central 
Oregon suggested that foraging activity was greatest in more open habitats in shrub steppe and pon¬ 
derosa pine forest-shrub ecotones (Dobkin et al., 1995). It has been suggested that these bats may 
favor edge habitats in Utah, particularly interfaces between juniper woodlands and sagebrush- 
grassland steppe (Sherwin et al., 2000), whereas in western Nevada foraging bats used pinon- 
juniper woodlands greater than availability of that habitat on the landscape (Ives, 2015). Occa¬ 
sional winter foraging by this species has been documented in Colorado (Ingersoll et al., 2010). 
A small sample of female Townsend’s big-eared bats radio tracked during spring and early 
summer in southeastern Idaho, prior to formation of maternity colonies, foraged in areas ranging 
from 24 to 61 hectares in the interface between sagebrush-steppe and juniper woodland, with for¬ 
aging areas less than 0.8 kilometers from night roosts (Haymond, 1998). Radio-tracking studies 
conducted in California suggest use of forests and heavily vegetated areas by foraging individuals 
(summarized by Pierson et al., 1999). In the Olema Valley of coastal California, Fellers and Pier¬ 
son (2002) radio tracked 17 and directly observed 21 light-tagged Townsend’s big-eared bats of 
both sexes and found that they flew around the perimeters of trees and foraged mostly along the 
edges of riparian woodlands rather than adjacent grazed grasslands. At Lava Beds National Mon¬ 
ument 15 individuals of both sexes (females were non-reproductive or post-lactating) were radio 
tracked to determine foraging patterns (Pierson and Fellers, 1998). Three of four males moved less 
than females, ranging within 3.0 kilometers of day roosts, and showed repeated nightly patterns 
favoring mountain mahogany (Cercocarpus sp.) habitats; females moved more widely (up to 14.0 
