O’SHEA, CRYAN & BOGAN: UNITED STATES BAT SPECIES OF CONCERN 
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(McCartney, 2007). McDonnell (2001) surveyed 990 bridges and culverts for use by bats in the 
Coastal Plain of North Carolina during summers 1997 and 1998 and found only 12 used as roosts 
by southeastern myotis, 11 housing solitary bats and one with seven bats; all were in swamp or bot¬ 
tomland hardwood forest habitats. Southeastern myotis were not found roosting under concrete 
slab bridges, I-beam bridges, steel multi-beam bridges, or steel pipe culverts, but they used chan¬ 
nel beam bridges, timber multi-beam bridges, T-beam bridges, and one concrete box culvert 
(McDonnell, 2001). 
Relatively little was known about the tree-roosting habits of this species until recently (Bar¬ 
clay and Kurta, 2007). Species of trees in which hollows have been used as roosts include black 
mangrove ( Avicennia nitida; Rice, 1957), bald cypress ( Taxodium distichum), American beech 
(Fagus grandifolia ), eastern cottonwood ( Populus deltoides), water tupelo ( Nyssa aquatica ), black 
gum ( Nyssa sylvatica), red maple (Acer rubrum ), white oak (Quercus alba), sweetgum (Liq- 
uidambar styraciflua), American sycamore (Platanus occidentalis ), and ash (Fraxinus sp.) 
(Whitaker and Hamilton, 1998; Hoffman, 1999; Clark, 2003; Gooding and Langford, 2004; 
Mirowsky et al., 2004; Carver and Ashley, 2008; Rice, 2009; Clement and Castleberry, 2013a; 
Fleming et al., 2013a; Stuemke et al., 2014). Southeastern myotis broadly overlap in habitat type 
with Rafinesque’s big-eared bats, but there is evidence that in some areas they may choose roosts 
in hollow trees with dissimilar characteristics to those used by Rafinesque’s big-eared bats (Steven¬ 
son, 2008; Trousdale, 2011). 
Trees used as roosts in bottomland hardwood forests at Noxubee National Wildlife Refuge in 
Mississippi had greater girth, greater cavity widths, lower cavity heights, and larger internal cham¬ 
bers than trees that had no evidence of use, but tree species and sizes were chosen randomly 
(Stevenson, 2008; see below for additional information on roosts in trees). In eastern Texas, tran¬ 
sect searches and radio tracking of three southeastern myotis showed that stands where roost trees 
were located were in areas with higher densities of smaller trees than stands supporting 
Rafinesque’s big-eared bats, but other aspects of roost trees did not differ between roosts used by 
the two species (Stuemke et al., 2014). However, compared to trees that were unused, roost trees 
used by both species were larger, had larger diameters and cavities, greater numbers of entrances, 
were in trees with entrances higher above ground, and were located in stands with higher numbers 
of large trees (Stuemke et al., 2014). In eastern Arkansas, two radio-tracked female southeastern 
myotis roosted with 32-104 conspecifics in two hollow, live water tupelo trees with large, trian¬ 
gular basal openings and enclosed ceilings (Hoffman, 1999). 
Winter Roosts: In the southern part of the distribution, southeastern myotis remain active 
throughout much of the winter (Humphrey and Gore, 1992) and are seldom found torpid except for 
brief periods (Lowery, 1974; Jones and Pagels, 1968). In northern parts of the range, in contrast, 
caves appear to be essential for winter hibernation. In southern Indiana, southeastern myotis have 
been found hibernating in caves during seven months of the year, and hibernation lasts four to five 
months in northwestern Florida caves (Rice, 1957). Hibernating colonies as large as 3,000 bats 
were reported from caves in western Kentucky (Harvey et al., 1991). Caves utilized in winter can 
be different from those used during warm seasons, and during winter they may be more concen¬ 
trated in fewer caves than utilized in summer (Humphrey and Gore, 1992). Up to 150 individuals 
were found hibernating in abandoned mines and old water wells in Arkansas (Davis et al., 1955; 
Heath et al., 1986; Saugey et al., 1989, 1993). 
During winter in peninsular Florida these bats do not usually undergo deep hibernation (but 
will do so in other parts of their range, and can become torpid during strong cold spells even in 
Florida). Although small numbers can be found in peninsular Florida caves during winter, many 
instead roost in small groups or as individuals in hollow trees and other structures (including build¬ 
ings and houses), and bats often roost near or over water within bridges, culverts, storm drains, and 
