Nyctinomops macrotis (big free-tailed bat)

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Big Free-Tailed Bat description

See Kumirai and Jones (1990) for a key to the species of NYCTINOMOPS.

Big Free-Tailed Bat habitats

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.


(Nowak, 1999)

Range elevation: 0 to 1800 m.

Habitat Regions: temperate ; tropical ; terrestrial

Terrestrial Biomes: desert or dune ; chaparral ; forest ; scrub forest

Aquatic Biomes: coastal

Other Habitat Features: suburban

Comments: Rocky areas in rugged country, at least in southwestern U.S. and Mexico. In Texas, most have been netted in lowlands of river floodplain-arroyo association; also in shrub desert and woodland habitats. Has been captured in evergreen forest at 2440 m in New Mexico. Mainly below 1800 m in southwestern U.S. In Mexico, taken over streams in areas of mixed tropical deciduous forest and thorn forest. Netted over a pool in thorn forest in Bolivia. Roosts in rock crevices (vertical or horizontal) in cliffs; also in buildings caves, and occasionally tree holes (Milner et al. 1990). Winter habits unknown. Maternity colonies occupy rock crevices. Evidently colonies may occupy the same crevice in successive years.

Big Free-Tailed Bat size

Length: 14 cm

Sexual Dimorphism: Males are slightly larger than females.

Range: 145-160 mm males; 120-139 mm females

Range: 22-30 g

Big Free-Tailed Bat distributions

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 )

occurs (regularly, as a native taxon) in multiple nations

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Big Free-Tailed Bat Conservation Status

Nyctinomops macrotis is not endangered, but is not common either.

Temperate North American bats are now threatened by a fungal disease called “white-nose syndrome.” This disease has devastated eastern North American bat populations at hibernation sites since 2007. The fungus, Geomyces destructans, grows best in cold, humid conditions that are typical of many bat hibernacula. The fungus grows on, and in some cases invades, the bodies of hibernating bats and seems to result in disturbance from hibernation, causing a debilitating loss of important metabolic resources and mass deaths. Mortality rates at some hibernation sites have been as high as 90%. While there are currently no reports of Nyctinomops macrotis mortalities as a result of white-nose syndrome, the disease continues to expand its range in North America.

US Federal List: no special status

CITES: no special status

IUCN Red List of Threatened Species: least concern

United States

Rounded National Status Rank: N3 - Vulnerable

Rounded Global Status Rank: G5 - Secure

Reasons: Widespread distribution from western North America to South America, but range apparently not continuous; presumably more than 100 occurrences; occurs on several protected sites.

Other Considerations: Occurrence criteria may vary among natural heritage programs. Some programs may consider roost sites as occurrences whereas others may use all collection records.

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