Roosting Ecology of Female Townsend's Big-Eared Bats (Corynorhinus townsendii) in South-Eastern British Columbia: Implications for Conservation Management

Differential selection of roosts by Eastern Small-footed Myotis (Myotis leibii) relative to rock structure and microclimate

“…Rock formations used by Eastern Small-footed Myotis were predominantly south-facing, devoid of tree canopy, and received direct solar radiation for much of the day. Similar conditions have been reported for rocky features used by Spotted Bat ( Euderma maculatum ; Chambers et al 2011 ), Townsend’s Big-eared Bat ( Corynorhinus townsendii ; Reid et al 2010 ), Pallid Bat ( Antrozous pallidus ; Schorr and Siemers 2013 ), Fringed Myotis ( M. thysanodes ; Lacki and Baker 2007 ), Western Long-eared Myotis ( Rancourt et al 2005 ), Western Small-footed Myotis ( M. ciliolabrum ; Rodhouse and Hyde 2014 ), and Canyon Bat ( Parastrellus hesperus ; Cross 1965 ). Rocks have high thermal inertia and when exposed to direct sunlight sometimes create microclimates that are warmer and more thermally stable than their surroundings ( Lausen and Barclay 2002 ).…”

“…Rock-roosts come in a diversity of forms and the factors that govern roost selection among the different types that are available are unclear ( O’Shea et al 2011 ; Andrews 2021 ). Studies from North America have reported bats roosting in cavernous openings in cliffs and deep interstitial voids between talus blocks or boulders ( Lacki et al 1994 ; Hurst and Lacki 1999 ; Reid et al 2010 ); in relatively narrow crevices or tubes in cliffs, bluffs, and other large masses of emergent bedrock ( Lausen and Barclay 2003 ; Rancourt et al 2005 ; Randall et al 2014 ); and in crevices between or under rocks at the surface of talus, scree, shale barrens, and under rocks sitting directly on bedrock ( Baker and Lacki 2006 ; Lacki and Baker 2007 ; Whitby et al 2013 ). The few studies that have directly assessed selection of microclimates by rock-roosting bats collectively report at least two kinds of thermal profiles–some rock-roosts have pronounced daily cyclical temperature fluctuations, whereas others have relatively stable thermal profiles that may be warmer or cooler than ambient air ( Chruszcz and Barclay 2002 ; Lausen and Barclay 2003 ; Solick and Barclay 2006 , 2007 ; Rambaldini and Brigham 2008 ; Schorr and Siemers 2013 ).…”

Habitat use of female gray bats assessed using aerial telemetry

“…Of the 100 female gray bats that were successfully tracked by fixed‐wing aircraft, 42 had >15 independent locations. This represents the largest sample size of any tracking study of gray bats (e.g., n = 14; Thomas and Best ) and any aerial tracking of bats (Reid et al , Chambers et al ). Moreover, Thomas and Best () reported a 22% success rate in gathering ≥2 locations on transmittered bats from the ground, whereas our success rate using the same parameters was 92%.…”

“…Aerial telemetry has been previously used in only 2 bat studies. Reid et al () located roosts when bats were stationary, whereas Chambers et al () tracked bats at night but with limited success (11 locations total from 5 individuals).…”