Nyctinomops macrotis
(Gray, 1839)

nic-tin-e-mops mac-rO-tis

The big free-tailed bat is about the size of a hoary bat and, therefore, large by Kansas standards. It is "free-tailed" in that the tail extends well beyond the posterior of the tail membrane. The dorsal pelage ranges from reddish-brown to dark brown to black, with individual hairs white at the base. The ventral pelage is slightly paler. The pelage looks almost greasy. The ears are large and joined basally at the midline of the forehead. Finally, the lips are wrinkled. The dental formula is inciisors 1/2, canine 1/1, premolars 2/2, molars 3/3.
The only other free-tailed bat in Kansas is the Brazilian free-tailed bat, from which the big free-tailed bat can be distinguished by its larger size and relatively longer ears. 

The big free-tailed bat ranges from central South America northward through Central America and Mexico into the southwestern United States. In Kansas, the species has been reported from Morton, Crawford, and Kiowa counties. However, voucher specimens for the distributional records in Crawford and Kiowa counties that were supposed to be in the departmental collection at Pittsburg State University evidently have been lost and are unavailable for examination. Based on published external measurements, the specimen from Kiowa County almost certainly was a Tadarida brasiliensis rather than a Nycticeius macrotis. The published measurements of the specimen from Crawford County are questionable and could apply to either species. In any event, it is doubtful that this species is a resident of Kansas. Big free-tailed bats have been found in at least Missouri and Iowa, well outside their range and in totally unsuitable habitat. These individuals have been interpretted as wanderers, pioneers, or scouts. When summer colonies break up in autumn, individual free-tailed bats (both species) show up in areas far outside the known range almost as if they are searching for new roost sites during the time when the population of this species is highest. It is assumed that most bats of this species in the United States spend the winter months in southwestern Texas, Arizona, and southern California.
Pleistocene and Holocene fossils of this species have been found in a cave in Cuba.
Pleistocene and Holocene fossils of this species have been found in a cave in Cuba.
Pleistocene and Holocene fossils of this species have been found in a cave in Cuba.

(, Museum Voucher) (, Observation) (, Literature Record)
Open icons are questionable records; Click on a marker to view details.
  • Occurrence Summary:  
  • 1 Total Records 
  • 1 Museum Vouchers 
  • 0 Other Observations 
Some county occurrences indicated below may be too imprecise to map above.
County Breakdown: County Name (# occurrences):
Morton (1);

Natural History:
In its typical habitats in the Southwest, this species roosts in crevices high on cliff faces. This permits the bat to fall and gain speed to provide lift for flight. This is necessary because big free-tailed bats have the narrowest, longest wings of any bat in the United States. With these long, narrow wings, they are adapted for fast, enduring flight in areas where maneuverability is not needed. This bat forages late at night, occasionally emitting a sharp, piercing call.
Adult measurements of big free-tailed bats are total length 120-160 mm, length of tail 40-57 mm; length of hind foot 7-11 mm; length of ear 25-32 mm; weight 22-30 g. Longevity in the species is not known.
This bat forages late at night, but sometimes is seen on the wing early in the afternoon. Its flight is straight and rapid, and the noise of its wings is sometimes audible as it flies overhead. It often emits a sharp, piercing call while foraging.
I found just one record of a skull of a big free-tailed bat removed from an owl pellet.

Occurrence Activity:
This species recently was transferred to the genus Nyctinomops from the genus Tadarida. Nyctinomops macrotis is monotypic in that no subspecies have been named. 

1952 Cockrum, E. L. Mammals of Kansas. Univ. Kansas Publ. Mus. Nat. Hist. 7:1-303. ():
1967 Hays, H. A., and P. H. Ireland A big free-tailed bat (Tadarida macrotis) taken in southeast Kansas The Southwestern Naturalist 12():196
1967 Jones, J. K. Jr., E. D. Fleharty, and P. B. Dunnigan The distributional status of bats in Kansas. Univ. Kansas Mus. Nat. Hist. Misc. Publ., 46:1-33. ():
1978 Hays, H. A., K. Phillips, and G. Salsbury A big free-tailed bat (Tadarida macrotis) taken in southcentral Kansas The Southwestern Naturalist 23():537-538
1990 Milner, Jr., C. Jones, and J. K. Jones, Jr. Nyctinomops macrotis Mammalian Species 351():1-4
1999 Wilson, D. E., and S. Ruff Smithsonian Institution Press, Washsington, DC. 1-750pp.
2000 Sparks, D. W., and J. R. Choate Distribution, natural history, conservation status, and biogeography of bats in Kansas Pages 173-228 in Reflections of a Naturalist: Papers Honoring Professor Eugene D. Fleharty Fort Hays State University, Hays, KS. pp.
2008 Timm, R. M., G. R. Pisani, J. R. Choate, N. A. Slade, G. A. Kaufman, and D. W. Kaufman, . pp.
Account Last Updated:
7/13/2017 10:14:28 AM

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