Eptesicus furinalis
Argentine Brown Bat
DESCRIPTION
Eptesicus furinalis (Figure 1) part of “big brown bats” is different from most
vespertilionids by having a large broad head, husky body, short rounded ears and short
broad wings. The ears and membranes are naked and dark in color. The face is plain
without a noseleaf and the tail is shorter than the head and body and completely ensheathed
within the uropetagium with the wing membranes starting at the toes (Emmons, 1990;
Kurta, 1996).
Depending on where this specie is found the coloration will vary. The dorsal fur
generally is blackish but can be dark brown with the venter being paler with sometimes a
yellowish and orange tint (Redford, 1992).
The skull has a flat rostrum with a little sagittal crest. The dental formula is i 2/3,
c 1/1, pm ½, m 3/3, total 32. The first upper incisor has a secondary cusp compared to the
second incisor which is half the length and has no cusp (Kurta, 1996).
The average body mass is 7.5-9g with the females being slightly larger than males
by 1.5g. The total length is 93-97mm, tail=37-39mm, hindfoot=9-10mm, ear=16mm,
body=52mm, and forearm length=38mm (Redford, 1992). There are seven subspecies of
this species.
DISTRIBUTION
Eptesicus furinalis is widely distributed throughout Central and South America.
There have been records of findings in Belize, Costa Rica, Guatemala, Honduras,
Nicaragua and Panama for Central America. South America has records for findings in
Argentina, Bolivia, Brazil, Colombia, Ecuador, French Guiana, Paraguay, Peru and
Venezuela. The northern most rage for Eptesicus furinalis is near Tamaulipas Mexico and
the southern most range is the Argentine province of La Pampa, about the 37˚ parallel
(Eisenberg, 1989; Kurta, 1996).
ONTOGENY AND REPRODUCTION
There are two breeding periods during the year for this species. The first period
occurs in late July and early August with a gestation period lasting about three months.
Copulation follows parturation thereby proving that females store sperm. The number of
embryos for the first pregnancy is 1.9 whereas the number for the second pregnancy is one.
The age at which this species becomes sexually mature and begins to reproduce is less than
one year (Redford, 1992).
ECOLOGY AND BEHAVIOR
Little is known about the habitat of this bat other than the data collected by accidental
captures in mist nets. This species is known to inhabit many biomes as Willeg et al’s
“Paraguayan Bat Assemblages” shows. The biomes are as follows: Alto Chaco, Bajo
Chaco, Campos Cerrados, Central Paraguay, Alto Parana, and Neembucu. These areas
have scrub forests, palm savannas, semi-arid regions, dense forests, grasslands, sub-humid
forests, and wetlands. They are generally known to be in higher altitudes of 1580m and
prefer moist habitats and montane tropical forests (Eisenberg, 1989).
This specie roosts under the bark of trees, within walls and floors, attics, and hollows in
trees. They are also known live in caves and go through daily torpor (Eisenberg, 1999;
Kurta, 1996)
The main diet of this bat consists of aerial insects and seems to be the first bat out
feeding due to the capture records in mist nets, being the first one captured.
There are two known parasites for this bat: Vampirolepis pandoensis a hymenolopid
cestode and the nycteribiid batfly Basilia wenzeli (Kurta, 1996)
LITERATURE CITED
Eiseberg, John F. 1989. Mammals of Neotropics: The Northern Neotropics. The
University of Chicago Press, Chicago and London. Vol 1, 449pp
Eiseberg, John F. and Redford, Kent H. 1999. Mammals of Neotropics: The Central
Neotropics. The University of Chicago Press, Chicago and London. Vol 3, 609pp
Emmons, Louise H. 1990. Neotropical Rainforest Mammals: A Field Guide. The
University of Chicago Press, Chicago and London. 281pp
Kurta, Allen, R, Mies, and D. G. King. 1996. Eptesicus furinalis. Mammalian Species.
No. 526, pp 1-7
Redford, Kent H and Eiseberg, John F. 1992. Mammals of Neotropics: The Southern
Cone. The University of Chicago Press, Chicago and London. Vol 2, 430pp
Reference written by Nathan Weitz, Biology 378 student. Edited by Christopher Yahnke.
Page last updated 08-05-05.
Figure 1. Eptesicus furinalis
Photo courtesy of Nancy Simmons.
Simmons@nmnh.org