Pocketed free-tailed bat

The pocketed free-tailed bat (Nyctinomops femorosaccus) is a species of bat in the family Molossidae found in Mexico and in Arizona, California, New Mexico, and Texas in the United States. They resemble the Brazilian free-tailed bat ("Tadarida brasiliensis") but differ morphologically. They are classified within the order Chiroptera. They are recognized as "un-threatened" by the IUCN and as "apparently secure" by Natureserve categories.[2]

Pocketed free-tailed bat
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Chiroptera
Family: Molossidae
Genus: Nyctinomops
Species:
N. femorosaccus
Binomial name
Nyctinomops femorosaccus
(Merriam, 1899)

Characteristics

The pocketed free-tailed bat shares similar features with the Brazilian free-tailed bat ("Tadarida brasiliensis") but is larger in size. The name is derived from a skin fold stretching from the medial side of the femur to the middle of the tibia. This fold produces a shallow pocket on the underside of the interfemoral membrane in the vicinity of the knee. Some defining characteristics include: Ears joined at the midline; second phalanx of the 4th digit is less than 5mm; anterior part of hard palate narrowly excised; upper incisors placed close together with longitudinal axes nearly parallel.[3]

The pocketed free-tailed bat also has a large broad head with grooved lips. The face has many stiff hairs with spoonlike tips. The ears are thick and leathery with the presence of a dominant tragus. Body dimensions: body length~112mm; feet~10mm; tail~46mm; ears~23mm; forearms~46mm. Body mass range is 10–14 g (0.35–0.49 oz).[4]

Habitat and Ecology

Like other bats, this species is insectivorous; they eat a variety of insects including Lepidoptera, Hymenoptera, Homoptera, Coleoptera, Hemiptera, Orthoptera, Diptera, and Neuroptera. One research article showed that because of the limited flight maneuverability of the pocketed free-tailed bat vs the Brazilian free-tailed bat allowed the latter a better predator advantage for certain species of insects (specifically beetles). It also showed that the insect species diet for the pocketed free-tailed bats varies with season. In June and July, Lepidoptera accounted for greatest volume of prey while diets in September and March consisting mostly of Hemiptera[5] Table 1. In the dry season, they seek drinking water from various open access water sources. The roosts are located in caves, crevices, mines, tunnels, and man-made structures [6] with colony sizes less than 100 individuals.[7]

Reproduction

Like other bats pocketed free-tailed bats exhibit delayed fertilization. They mate just prior to ovulation in the spring.[8] Their young are born in early July. The gestation period is about 70 to 90 days and when the young are finally born, they weigh 3-4 grams, or about 22% of the adult weight.[9] This new generation is able to fly within 1-1.5 months[10]

References
  1. Arroyo-Cabrales, J. & Ticul Alvarez Castaneda, S. (2008). "Nyctinomops femorosaccus". IUCN Red List of Threatened Species. 2008. Retrieved 7 February 2010.CS1 maint: ref=harv (link)
  2. Goodenough, Anne E. (2012). "Differences in two species-at-risk classification schemes for North American mammals" (PDF). Journal for Nature Conservation. 20 (2): 117–124. doi:10.1016/j.jnc.2011.11.001.
  3. Pocketed Free-tailed Bat. Pocketed Free-tailed Bat. Texas Parks and Wildlife, 01 Jan. 2012. Web. 21 Mar. 2015.
  4. Lancaster, Eric. "Nyctinomops Femorosaccus Pocketed Free-tailed Bat." Nyctinomops Femorosaccus Pocketed Free-tailed Bat. University of Michigan, 17 Feb. 2000. Web. 21 Mar. 2015.
  5. Matthews, A. K.; Neiswenter, S. A.; Ammerman, L. K. (2010). "Trophic Ecology of the Free-tailed Bats Nyctinomops femorosaccus and Tadarida brasiliensis (Chiroptera: Molossidae) in Big Bend National Park, Texas". The Southwestern Naturalist. Southwestern Association of Naturalists. 55 (3): 340–346. doi:10.1894/JKF-08.1.
  6. Melanie Bucci; Yar Petryszyn; Paul R. Krausman (2011). "Bat Occurrence and Use of Archaeological Sites at Three National Monuments in Central Arizona". Journal of the Arizona-Nevada Academy of Science. 43 (1). Arizona-Nevada Academy of Science. pp. 1–5. JSTOR 41510539.
  7. Arroyo-Cabrales, J.; Álvarez-Castañeda, S.T. (2008), Nyctinomops femorosaccus. The IUCN Red List of Threatened Species
  8. "Insectivorous Bats." National Park Service, U.S. Department of the Interior, 2 Apr. 2015. Web. 6 Apr. 2015.
  9. Grzimek, Bernhard (1990). Grzimek's Encyclopedia of Mammals Volume 3. McGraw-Hill Publishing. ISBN 9780079095084.
  10. Wilson, D.E.; Ruff, S. (1999). Smithsonian Book of North American Mammals. Washington, D.C.: Smithsonian Institution Press.
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