O’SHEA, CRYAN & BOGAN: UNITED STATES BAT SPECIES OF CONCERN 
73 
Eumops underwoodi — Underwood’s bonneted bat (Family Molossidae) 
Conservation Status. — National and International Designations: U.S. Fish and Wildlife 
Service (1994, 1996a,b): Species of Concern (inactive, former Category 2 candidate for listing 
under the U.S. Endangered Species Act). International Union for the Conservation of Nature 
(2017): Least Concern. NatureServe (2017): Rounded Global Status G4, Apparently Secure. 
State Designations: Arizona Game and Fish Department (2012): Tier IB Species of Greatest 
Conservation Need. 
Description. — Under¬ 
wood’s bonneted bat (Fig. 15) is 
the second largest bat in the Unit¬ 
ed States, being only slightly 
smaller than the greater bonneted 
bat (see account above). Under¬ 
wood’s bonneted bat is distin¬ 
guishable from the greater bon¬ 
neted bat externally based on the 
presence of stiff bristles (guard 
hairs) on the rump in E. under¬ 
woodi. Ears are set close together 
but are not joined on the fore¬ 
head. Upper lips are smooth. As 
in other molossids, the tail is free 
from the interfemoral membrane, 
the ears are large, rounded and 
extended forward, and the wings 
are long and narrow. The dorsal 
pelage can be various shades of 
brown, whereas the ventral 
pelage tends to be gray. Body 
mass of Arizona specimens range 
from 53.0 to 65.3 grams (Cockrum and Gardner, 1960), and forearm lengths 66.9-73.7 millimeters 
(Hoffmeister, 1986). Unlike many species of U.S. bats, males are slightly larger than females (Eger, 
1977). 
Distribution and Systematics. — Underwood’s bonneted bat is found primarily in the 
Neotropics, from Nicaragua north to Sonora and Baja California in Mexico and extreme southern 
Arizona. The latter is the only area of occurrence in the United States (Fig. 16; Kiser, 1995; Cortes- 
Calva et al., 2012). The first U.S. record was a specimen shot over a pond near Sasabe in Pima 
County, Arizona in 1954 (Baker, 1956b). The second and third U.S. specimens were taken in 1957 
over water in the same region of Arizona but at the southwestern flank of the nearby (less than 
approximately 40 kilometers) Baboquivari Mountains (Hoffmeister, 1959), and 16 more specimens 
were taken by mist net in 1958 near the same location as the first record, which was a few hundred 
meters north of the border with Sonora, Mexico (Cockrum and Gardner, 1960). Underwood’s bon¬ 
neted bat has been captured in the region more frequently since the 1950s, particularly by mist net 
at the large, permanent Quitobaquito Spring along the Sonoran border in Organ Pipe Cactus 
National Monument (for example, Petryszyn and Cockrum, 1990). Quitobaquito Spring is about 
130-155 kilometers west of the original capture locations near Sasabe and the Baboquivari Moun¬ 
tains. Hoffmeister (1970) reported that the presence of this species in southern Arizona was sea- 
Figure 15. Underwood’s bonneted bat, Eumops underwoodi (photo by J. 
Scott Altenbach). 
