Description: The big free-tailed bat, like its close relative, the Brazilian free-tailed bat, can be distinguished from other Kansas bats by the "free" tail extending beyond its tail membrane. It is separated from the Brazilian free-tailed bat by having relatively longer ears. The big free-tailed bat has long hair, light reddish to dark brown in color; the underparts are lighter than the dorsum. The hair texture is velvety and somewhat greasy when touched. The ears are united for a short distance at the point where they meet on the forehead. The membranes, ears, and muzzle are black. This rare bat is larger (over 325 mm in wingspread) model of the more common Brazilian free-tailed bat. Its tail extends at least one half its length beyond the tail membrane. Its narrow wing is well designed for rapid flight. The sexes are alike.
Size: The measurements of a typical specimen are: total length 124 mm; tail 50 mm; hind foot 11 mm; ear 28 mm; weight 20 grams.
Range and Habitat: The big free-tailed bat is a migratory species in Kansas, and spends its winters in warmer parts of the continent. Only three specimens have been reported from southern Kansas, but this bat may be found in other parts of the state, and it is also known from Iowa. Elsewhere, it usually inhabits rocky country.
Breeding: Nothing is known about the reproduction of this bat in Kansas. Elsewhere, females form nursery colonies, and a single young is born in May after a gestation period of approximately three months.
Food: 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.
Remarks: This species has recently been transferred to the genus Nyctinomops from Tadarida.