Nyctinomops femorosaccus (Pocketed Free-tailed Bat)

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Pocketed Free-Tailed Bat description

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

Pocketed Free-Tailed Bat habitats

Habitat and Ecology

This species is insectivorous; it eats a variety of insects (Lepidoptera, Hymenoptera, Homoptera, Coleoptera, Hemiptera, Orthoptera, Diptera and Neuroptera). During the dry season it utilizes water sources with open access and a large available surface area from which to drink. It leaves its roosts after dark and is usually not taken in mistnets until two or three hours after sunset. It roosts in caves, rock crevices in cliff faces and man-made structures. Colonies usually number fewer than 100 individuals. It gives birth to only one young per year, usually in early July, and the young are flying in mid to late August (Wilson and Ruff 1999).

  • Terrestrial

This species inhabits semiarid desertlands. Their roosts can be found in caves, tunnels, mines, and rock crevices. They have also been found hanging under the roof tiles of buildings. They are usually found in large colonies. (Vaughn, Ryan, Czaplewski, 1999)

Terrestrial Biomes: desert or dune ; chaparral

Comments: Usually associated with rugged canyons, high cliffs, and rock outcroppings. Roosts in rock crevices and caves during the day; may also roost in buildings or under roof tiles. Has been taken in desert shrubland, over waterhole surrounded by mixed tropical deciduous and thorn forest (Sonora, Mexico), in floodplains with much sycamore and mesquite, in areas adjacent to high cliffs, and in pine-oak forest at 2160 m (Feb. in Jalisco) (Kumirai and Jones 1990). Winter habits poorly known.

Pocketed Free-Tailed Bat size

Length: 10 cm

Weight: 15 grams

Sexual Dimorphism: None

Average: 109 mm
Range: 99-118 mm

Range: 13.8-17 g

Pocketed Free-Tailed Bat distributions

This species occurs from Guerrero (Mexico) to New Mexico, Arizona, California (USA) and Baja California (Mexico; Simmons 2005). It occurs from lowlands to 2,250 m asl (Wilson and Ruff 1999).

Nyctinomops femorosacca, the Pocketed Free-tailed Bat, is a member of the Molossidae. It inhabits the southwestern United States and northwestern Mexico. The bat has been seen in southern Arizona, southern California, southeastern New Mexico, western Texas, and into Mexico to the state of Michoacan. ( )

Biogeographic Regions: nearctic (Native )

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

Pocketed Free-Tailed Bat Conservation Status

Red List Category
Least Concern

Red List Criteria


Year Assessed

Arroyo-Cabrales, J. & lvarez-Castaeda, S.T.

Solari, S.


This species is listed as Least Concern because of its wide distribution, presumed large subpopulations in some localities and occurrence in a number of protected areas.

  • Least Concern (LC)
  • 1996
    Lower Risk/least concern (LR/lc)

The status of the Pocketed Free-tailed Bat is not known. They are undoubtedly being threatened by the habitat modification and pesticide dispersal by humans. (Grzimek, 1990) There are no conservation projects underway specifically for Nyctinomops femorosacca.

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 femorosaccus 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

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