O’SHEA, CRYAN & BOGAN: UNITED STATES BAT SPECIES OF CONCERN 
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Conservation Need. California 
Department of Fish and Wildlife 
(2017): Special Animals List, 
Species of Special Concern. 
Nevada Department of Conser¬ 
vation and Natural Resources 
(2015b): Sensitive Mammal, 
Critically Imperiled. Texas Parks 
and Wildlife (2012): Species of 
Greatest Conservation Need. 
Description. — The greater 
bonneted bat (Fig. 13) is the 
largest bat found in the continen¬ 
tal United States. The forearm 
length ranges 73 to 83 millime¬ 
ters, wingspan ranges 530 to 570 
millimeters, and body masses up 
to 73 grams have been recorded 
(Barbour and Davis, 1969; Eger, 
1977; Best et al., 1996). Unlike 
many species of U.S. bats, males 
are slightly larger than females Figure 13. Greater bonneted bat, Eumops perotis (photo by J. Scott 
(Eger, 1977). The greater bonnet- Altenbach). 
ed bat is a typical molossid bat in morphology, with the distal half of the tail free from the inter- 
femoral membrane, long narrow wings, and large rounded ears that are not erect. The ears are 
joined at the midline and extend forward beyond the nose, acting as crude airfoils 1.5 times as wide 
as high (Vaughan, 1959). Coloration varies from gray to brownish gray, with melanism also report¬ 
ed (Krutzsch, 1955). A gland is present on the throat and can be well-developed seasonally in males 
(Howell, 1920b; Krutzsch, 1955). 
Distribution and Systematics. — In the United States, the greater bonneted bat has been 
reported in California, Nevada, Arizona, southern New Mexico, and southern Texas (Fig. 14; Cock- 
rum, 1960; Rowlett, 1972; Best et al., 1996). Formerly thought to be limited to the southern part 
of the state, acoustic surveys have confirmed their occurrence at multiple locations in northern and 
central California, including the Sierra Nevada and Coast Ranges, with some colonies likely resi¬ 
dent year-long (Pierson and Rainey, 1998c). Additional records from much of California also have 
accumulated based on specimens submitted for rabies diagnostics (Constantine, 1998a). One sub¬ 
species is recognized in North America, Eumops perotis californicus, and two subspecies in South 
America (Best et al., 1996). Best et al. (1996) provided a complete taxonomic synonymy of past 
scientific names applied to the greater bonneted bat. The generic name Eumops comes from the 
Greek word meaning “good” and the Malay word meaning “bat”. The specific epithet perotis 
comes from the Latin word for “through” and the Greek word for “ear”. Other English common 
names include greater western mastiff bat, greater mastiff bat, western bonneted bat, western mas¬ 
tiff bat, and California mastiff bat. 
Habitats and Relative Abundance.— The greater bonneted bat has commonly been report¬ 
ed from desert life zones in the southwestern U.S., with elevation ranges from 60 meters below sea 
level in California to 1,100 meters in Texas, but it also is found in forested areas (Best et al., 1996; 
Pierson and Rainey, 1998c; Siders et al., 1999). Roost locations have been found in chaparral and 
