120 
PROCEEDINGS OF THE CALIFORNIA ACADEMY OF SCIENCES 
Series 4, Volume 65, Supplement I 
to locate roosts have emphasized females as described below, but two males were observed roost¬ 
ing in a small fissure in a cliff face in southeastern Montana (Jones et al., 1973), one was found 
roosting under bark of a tree in southern British Columbia, and nine were found roosting under 
bark of tree stumps in the same region (Vonhof and Barclay, 1996, 1997). 
Winter Roosts: Winter roosts of long-eared myotis are not well known, although they were 
among the species of bats reportedly found most commonly in surveys of inactive mines (presum¬ 
ably including winter) in Colorado (Navo et al., 2000). In Washington and Oregon, these bats were 
infrequently encountered hibernating during intensive searches of 650 caves or mines during win¬ 
ters 1982-1989, with just four solitary bats found roosting at three caves (Perkins et al., 1990). Two 
solitary individuals were reported from another cave near Mount St. Helens, Washington (Senger 
et al., 1974), and two bats were reported hibernating in a mine in northeastern Montana (Swenson 
and Shanks, 1979). One record of an apparently hibernating long-eared myotis was from a garage 
in Corvallis, Oregon during December (Perkins et al., 1990). Three l im estone caves in northern 
California had one to five hibernating individuals in each (Marcot, 1984). Bridges were used as 
winter roosts of this species in the central Sierra Nevada of California (elevations greater than 
1,000 m; Pierson et al., 2001). No bats of this species were observed hibernating in abandoned 
mines in the White and Inyo Mountains of California and Nevada (Szewczak et al., 1998). 
Long-eared myotis occasionally leave hibemacula during winter: Lausen and Barclay (2006) 
detected echolocation calls of flying bats of this species during winter in the arid prairies of south¬ 
ern Alberta, an area devoid of significant caves. Small numbers were captured in mist nets at the 
mouth of Azure Cave at 1,361 meters elevation in Montana during September (Hendricks et al., 
2000 ). 
Given the lack of extensive records of long-eared myotis hibernating in caves or mines in sig¬ 
nificant numbers and their propensity to roost in crevices and crevice-like situations in warm sea¬ 
sons (see below), we suspect that in many areas these bats hibernate in small numbers in deep rock 
crevices, similar to big brown bats in western North America (Lausen and Barclay, 2006; Neubaum 
et al., 2006; Kliig-Baerwald et al., 2017) and as was postulated for western bats in general by 
Twente (1960). Those captured and radio tagged in early autumn in Yellowstone National Park 
roosted in ground-level rock crevices in rock fields or in crevices in lower canyon walls until tags 
no longer functioned (Johnson et al., 2017). 
Warm Season Roosts in Rock and Soil Crevices and Cavities: Rock crevices were the pre¬ 
ferred roosts of reproductive females in the pinon-juniper woodlands of Mesa Verde National Park 
in southwestern Colorado (Snider et al., 2013). Radio tracking of 15 females led to discovery of 33 
roosts in rock crevices and one roost in a juniper snag, with roosts less than 2 meters above ground 
level. These bats roosted in small groups of three or fewer and switched roosts frequently, with an 
average distance of 424 meters (range 31-1,427 meters) between successive roosts. Despite exten¬ 
sive areas of recently burned forest, all but two roosts were in unbumed habitat; occupied rock 
crevices were on average 118 centimeters higher and 24 centimeters deeper than unoccupied, ran¬ 
domly chosen rock crevices (Snider et al., 2013). On the landscape scale, distance to nearest water 
and distance to burned habitat were the most important variables related to roost use by long-eared 
myotis at Mesa Verde National Park, with occupied roosts on average 1,251 meters closer to water 
and 345 meters farther from burned habitat than unoccupied crevices. Ten roosts found by radio 
tracking three individuals in the Jemez Mountains of New Mexico ranged 1,585 to 2,542 meters in 
elevation and were 0.3 to 1.0 kilometers from the point of capture, with five roosts of adult females 
in rock crevices, and five roosts used over an eight-day period by the single male including both 
snags and rock crevices; rock crevices utilized as roosts were on or near the ground (Bogan et al., 
1998). 
