By James Lawrence
Geographic Range
The big free tailed bat has been found as far north as southwestern British Colombia and as far east as South Carolina. Nyctinomops macrotis ranges from southwestern North America, through northern and central Mexico, throughout South America. It has also been found on Cuba, Jamaica, and Hispanola.
(Parish, D.A., 1999; Nowak, 1999)
Biogeographic Regions:
nearctic 
(native ); neotropical (native ).
Habitat
(5904 ft)
Nyctinomops macrotis mainly inhabits rugged and rocky terrain. They are a migratory species that travels seasonally from Mexico to the southwestern United States (Texas, Arizona, California, Nevada, Colorado) . They prefer rocky cliffs in weathered rock fissures and crevices. They have also been discovered roosting in buildings and in terrestrial plants including ponderosa pines, douglas firs, and desert shrubs.
A nursery colony in the Chisos mountains in Brewster County, Big Bend National Park has become quite famous.
(
http://www.nsrl.ttu.edu/tmot1/nyctmacr.htm)
(Nowak, 1999)
These animals are found in the following types of habitat:
temperate ; tropical ; terrestrial .
Terrestrial Biomes:
desert or dune ; chaparral ; forest ; scrub forest .
Aquatic Biomes:
coastal .
Other:
suburban .
Physical Description
(0.77 to 1.06 oz; avg. 0.84 oz)
(4.72 to 6.3 in)
(16.42 to 17.17 in; avg. 16.81 in)
Adult males of this species range in head-body length from 145-160 mm, females are smaller (120-139 mm, approx. avg. 132).
The coat of Nyctinomops macrotis is very velvety, glossy, seemingly almost greasy to the touch. The coat is bi-colored, dorsally dark red to dark brown and ventrally substantially lighter.
The wings are long and narrow, and the membrane of the wing is thin and leathery. The tail extends freely somewhere between 40 to 52 mm behind the small tail membrane. The face of Nyctinomops macrotis is black; the ears lay forward and are joined at their bases on top of the head; the muzzle is fairly thin; and the upper lip is very furrowed. The legs of Nyctinomops macrotis are short and very strong.
The dentition of Nyctinomops macrotis is: 1/2 1/1 1/2 3/3
(http://www.ukans.edu/~mammals/nyctic-macr.html;
Some key physical features:
endothermic ; bilateral symmetry .
Sexual dimorphism: male larger.
Reproduction
Late winter / early spring
Once impregnated the females and males tend to part ways. Females separate themselves from the males, and each of the sexes form cave colonies amongst themselves
- (http://www.nsrl.ttu.edu/tmot1/nyctmacr.htm; Parish, D.A. and Jones C., 1999;
- Nowak, 1999; Klingel, J., 2000 http://www.fw.vt.edu/fishex/nmex_main/species/050037.htm)
The mating season for Nyctinomops macrotis lasts for only a few weeks in the mid to late winter. The female gives birth to a single young sometime in early to mid summer, in mid to late June..
- (http://www.nsrl.ttu.edu/tmot1/nyctmacr.htm;
- Parish, D.A. and Jones C., 1999;
Nowak, 1999;
Klingel, J., 2000 http://www.fw.vt.edu/fishex/nmex_main/species/050037.htm)
Key reproductive features:
gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (internal ); viviparous .
The care of the infant is the responsiblity of the females. After conception, the females rely partly on stored body fat and their colony to provide for the unborn infant. After birth, the lactating female provides for her offspring until it is able to function as an adult, which takes somewhere in the range of 2 to 3 months. The development of the offspring is quite rapid; a young bat is very close to full grown and able to fly by October, at an age of 3 to 4 months.
- (http://www.nsrl.ttu.edu/tmot1/nyctmacr.htm; Parish, D.A. and Jones C., 1999;
- Nowak, 1999;
Klingel, J., 2000 http://www.fw.vt.edu/fishex/nmex_main/species/050037.htm)
Parental investment:
altricial ; female parental care .
Behavior
Nyctinomops macrotis is strictly nocturnal. It only leaves the roost after sundown to forage for food. They are solitary hunters for the most part but have been known to hunt in small groups. They are particularly strong fliers and have a tendency to wander, which can put them into residential homes. This also may cause the extremes of their geological range. Nyctinomops macrotis tends not to be that aggressive, but do attempt to bite if cornered or handled.
(Parish, D.A. and Jones C., 1999; http://www.nsrl.ttu.edu/tmot1/nyctmacr.htm)
Food Habits
The big free tailed bat feeds primarily on large moths, though it has been known to hunt ground dwelling insects including crickets, stinkbugs, and flying ants. They can be heard when hunting emitting a piercing chatter (audible to humans at a range over 20 kHz)
(http://www.nsrl.ttu.edu/tmot1/nyctmacr.htm;
Parish, D.A. and Jones C., 1999; Best, T.L.,Harvey M.J., Altenbach J.S., and Sanchez-Brown, T.,
Primary Diet:
carnivore (insectivore ).
Economic Importance for Humans: Positive
Big free tailed bats probably help control populations of pest insects.
Ways that people benefit from these animals:
ecotourism ; produces fertilizer; controls pest population.
Conservation Status
IUCN Red List: [link]:
Lower Risk - Least Concern.
US Federal List: [link]:
No special status.
CITES: [link]:
No special status.
Nyctinomops macrotis is not endangered, but is not common either.
Other Comments
The species Nyctinomops macrotis was recently transferred to the genus Nyctinomops from Tadarida.
In the civil war guano was collected and used as a base compound to make gunpowder by the Confederate army.
(http://www.ukans.edu/~mammals/nyctic-macr.html; Nowak,1999)
For More Information
Find Nyctinomops macrotis information at
Contributors
James Lawrence (author), University of Michigan.
Kate Teeter (editor), University of Michigan.
