O’SHEA, CRYAN & BOGAN: UNITED STATES BAT SPECIES OF CONCERN 
33 
“Roosting habits” above). Most of the early information on population trends in Rafinesque’s big- 
eared bats is anecdotal and suggestive of declines or rarity. Belwood (1992:287) stated that in Flori¬ 
da this species “does not seem to be abundant anywhere in the state, is rarely seen, and is uncom¬ 
mon in collections”. Ellison et al. (2003) compiled data from all then-available sources on esti¬ 
mates of colony sizes for Rafinesque’s big-eared bat and found only five colonies with counts on 
at least four annual occasions. None of these showed significant trends. More recently, 1,138 roost¬ 
ing sites range-wide from 1864 to 2009 have been documented for this species, but this informa¬ 
tion has not been assessed for trend estimation (Bayless et al., 2011; Lacki and Bayless, 2013). 
Jones and Suttkus (1975) noted that when Rafinesque’s big-eared bats are found at scattered 
locations in the southeast they are mostly in low numbers, and that very few nursery colony loca¬ 
tions had ever been reported at the time of their review. Since then nursery colonies of 6-80 adult 
females were documented in eastern North Carolina, where one past colony may have been as high 
as 300 (Clark, 1990); one colony of “several hundred” is known from a building in South Caroli¬ 
na (Menzel et al., 2003:132). Other more recent efforts have found additional nursery colonies in 
multiple areas throughout the distribution (see “Roosting habits” above), with maximum colony 
sizes of 80-100 reported in hollow trees (Clark, 1990,2003; Lance et al., 2001; Gooding and Lang¬ 
ford, 2004; Johnson et al., 2012a; Lucas et al., 2015) and 118 in a cave (Hurst and Lacki, 1999). A 
total of 700-800 Rafinesque’s big-eared bats were counted at 13 maternity colony sites in Mam¬ 
moth Cave National Park in Kentucky (Bayless et al., 2011). Forty-two roosting sites in a variety 
of bridges, buildings, and hollow trees in Mississippi during 2001-2009 held maternity colonies 
ranging in size from four to 160 bats, with the latter group sharing four roost trees (Trousdale et 
al., 2008; Martin et al., 2011). 
The largest known winter concentrations of these bats occur in 10 hibemacula in the 
Appalachian Mountains and central plateau of Kentucky, North Carolina, and Tennessee, where 
about 4,100 Rafinesque’s big-eared bats have been counted in winter (Bayless et al., 2011). Sasse 
et al. (2011) provide winter count data of Rafinesque’s big-eared bats at 37 abandoned wells used 
as hibemacula in Arkansas (maximum count of 103 at one well) that suggest a decline over a 21- 
year period of observation. A search of 21 caves in the Alabama coastal plain during winter 1988 
resulted in observations of just two individuals in one cave; only one bat was found during a sub¬ 
sequent visit in 1990 (Best et al., 1992). Rafinesque’s big-eared bats were not found in searches of 
22 caves in Mississippi during 2005-2007 (McCartney, 2007), but a winter roost in a tree cavity in 
Mississippi held over 200 individuals (Stevenson, 2008). 
Increased efforts over the past decade have allowed more quantitative estimation of the prob¬ 
ability of detecting colonies of these bats (see also “Roosting habits” above). In Mississippi, Flem¬ 
ing et al. (2013b) estimated that searches for roost trees of both this species and the southeastern 
myotis had detection probabilities above 90%, but that visual estimates of colony size by inspect¬ 
ing internal cavities underestimated numbers of bats compared to digital imagery, with increased 
error in larger colonies. Comer et al. (2014) compared detection probabilities for Rafinesque’s big- 
eared bats using acoustic sampling versus roost search transects in eastern Texas piney woods habi¬ 
tat and found that 18 nights of acoustic surveys (using two detectors) would yield a detection prob¬ 
ability of 90%, whereas 56 one-kilometer length transects would be required to attain the same 
detection probability. 
In contrast, Clement and Castleberry (2011) reported that detection of Rafinesque’s big-eared 
bats in their Georgia study region was more cost-effective using roost surveys, followed by mist 
netting, with acoustic surveys least cost-effective. Clement and Castleberry (2013d) estimated 
abundance and density of colonies of Rafinesque’s big-eared bats across eight study sites in flood- 
plain forests in Georgia using a modeling approach that combined results of transect surveys for 
