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 The Mammals of Texas - Online Edition

ORDER CHIROPTERA:

BATS

Chiroptera, "hand wing," alludes to the great elongation of the fingers that support the flying membrane. Among mammals, bats are unique in that they have true powers of flight; other mammals, such as flying squirrels, volplane or glide, always from a higher to a lower elevation.

Bats as a group are crepuscular or nocturnal; their eyes are small and inefficient, but their ears are usually well developed. Experiments suggest that the middle and inner ear and high-frequency vocals are highly important in guiding bats in flight and in their aerial feeding activities. Some bats hibernate in winter; others migrate seasonally.

In the temperate regions, the young are born in late spring; in the tropics there appears to be no definite breeding season — young bats may be found in every month of the year. Most bats feed on insects, but some kinds feed regularly on fruits, nectar, or fish, and some, the vampire bats, are peculiarly adapted to feed on blood.

Bats are nearly worldwide in distribution. The tropical regions are best suited for them, and there the greatest variety is found. The temperate regions are inhabited by fewer species; no bats have been recorded in the Arctic and Antarctic regions. Thirty-two species of bats occur in Texas.

In addition to the 32 species of bats living in Texas today, four others are known from fossil skeletal remains. One of these, Myotis rectidentis, is extinct, but the other three — Myotis evotis, Macrotus californicus, and Desmodus rotundus — still occur in other parts of the continent. The range of Myotis evotis includes almost all of the western United States from the Great Plains westward; the leaf-nosed bat Macrotus occupies a range from the southern parts of Arizona, Nevada, and California southward into Mexico; and Desmodus, the common vampire, occurs in Mexico and has been found recently about 200 km south of the Texas border near Jimenez, Tamaulipas. Intensive search may reveal the presence of both Macrotus and Desmodus in Texas.

Family Mormoopidae (mormoopid bats)

Ghost-faced Bat, Mormoops megalophylla

Family Phyllostomidae (leaf-nosed bats)

Mexican Long-nosed Bat, Leptonycteris nivalis
Mexican Long-tongued Bat, Choeronycteris mexicana
Hairy-legged Vampire, Diphylla ecaudata

Family Vespertilionidae (vespertilionid bats)

Southeastern Myotis, Myotis austroriparius
California Myotis, Myotis californicus
Western Small-footed Myotis, Myotis ciliolabrum
Little Brown Myotis, Myotis lucifugus
Northern Myotis, Myotis septentrionalis
Fringed Myotis, Myotis thysanodes
Cave Myotis, Myotis velifer
Long-legged Myotis, Myotis volans
Yuma Myotis, Myotis yumanensis
Silver-haired Bat, Lasionycteris noctivagans
Western Pipistrelle, Pipistrellus hesperus
Eastern Pipistrelle, Pipistrellus subflavus
Big Brown Bat, Eptesicus fuscus
Western Red Bat, Lasiurus blossevillii
Eastern Red Bat, Lasiurus borealis
Hoary Bat, Lasiurus cinereus
Southern Yellow Bat, Lasiurus ega
Northern Yellow Bat, Lasiurus intermedius
Seminole Bat, Lasiurus seminolus
Evening Bat, Nycticeius humeralis
Spotted Bat, Euderma maculatum
Rafinesque’s Big-eared Bat, Plecotus rafinesquii
Townsend’s Big-eared Bat, Plecotus townsendii
Pallid Bat, Antrozous pallidus

Family Molossidae (free-tailed bats)

Brazilian Free-tailed Bat, Tadarida brasiliensis
Pocketed Free-tailed Bat, Nyctinomops femorosacca
Big Free-tailed Bat, Nyctinomops macrotis
Western Mastiff Bat, Eumops perotis

KEY TO THE BATS OF TEXAS

1.
  • Distinct, upwardly and freely projecting, triangular-shaped nose leaf at end of elongated snout: 2
  • Nose leaf absent, indistinct, or modified as lateral ridges or low mound-like structure; snout normal: 3
2.
  • Tail evident, projecting about 10 mm from dorsal side of interfemoral membrane; distance from eye to nose about twice distance from eye to ear; forearm less than 48 mm: Choeronycteris mexicana (Mexican long-tongued bat).
  • Tail not evident; eye about midway between nose and ear; forearm more than 48 mm: Leptonycteris nivalis (Mexican long-nosed bat).
3.
  • Thumb longer than 10 mm; hair straight, lying smoothly, glossy tipped: Diphylla ecaudata (hairy-legged vampire).
  • Thumb less than 10 mm; hair slightly wooly, pelage lax, not usually lying smoothly, not glossy tipped: 4
4.
  • Prominent grooves and flaps on chin; tail protruding from dorsal surface of interfemoral membrane: Mormoops megalophylla (ghost-faced bat).
  • No notable grooves or flaps on chin; lumps above nose or wrinkled lips possible, most faces lacking even these characteristics; tail extending to or beyond the edge of the interfemoral membrane: 5
5.
  • Tail extending conspicuously beyond free edge of interfemoral membrane: 6
  • Tail extending to free edge of interfemoral membrane: 9
6.
  • Forearm more than 70 mm; upper lips without deep vertical grooves: Eumops perotis (western mastiff bat).
  • Forearm less than 70 mm; upper lips with deep vertical grooves: 7
7.
  • Forearm less than 52 mm: 8
  • Forearm more than 52 mm (58-64): Nyctinomops macrotis (big free-tailed bat).
8.
  • Ears not united at base; second phalanx of fourth finger more than 5 mm: Tadarida brasiliensis (Brazilian free-tailed bat).
  • Ears joined at base; second phalanx of fourth finger less than 5 mm: Nyctinomops femorosacca (pocketed free-tailed bat).
9.
  • Ears proportionally large, more than 25 mm from notch to tip: 10
  • Ears of normal size, less than 25 mm from notch to tip: 13
10.
  • Color black with three large white spots on back, one just behind each shoulder, the other at the base of the tail: Euderma maculatum (spotted bat).
  • Color variable, but not black; no white spots on back: 11
11.
  • Dorsal color pale yellow; no distinctive glands evident on each side of the nose. Antrozous pallidus (pallid bat).
  • Dorsal color light brown to gray; distinctive glands (large bumps) evident on each side of the nose: 12
12.
  • Hairs on belly with white tips; strong contrast in color between the basal portions and tips of hairs on both back and belly; presence of long hairs projecting beyond the toes; known from eastern one-third of state: Plecotus rafinesquii (Rafinesque’s big-eared bat).
  • Hairs on belly with pinkish buff tips; little contrast in color between basal portions and tips of hairs on both back and belly; absence of long hairs projecting beyond the toes; known from western half of state: Plecotus townsendii (Townsend’s big-eared bat).
13.
  • At least the anterior half of the dorsal surface of the interfemoral membrane well furred: 14
  • Dorsal surface of interfemoral membrane naked, scantily haired, or at most lightly furred on the anterior third: 20
14.
  • Color of hair black, with many of the hairs distinctly silver-tipped: Lasionycteris noctivagans (silver-haired bat).
  • Color various, but never uniformly black: 15
15.
  • Color yellowish: 16
  • Color reddish, brownish, or grayish (not yellowish): 17
16.
17.
  • Forearm more than 45 mm; color wood brown heavily frosted with white: Lasiurus cinereus (hoary bat).
  • Forearm less than 45 mm; upper parts reddish or mahogany: 18
18.
  • Upper parts brick red to rusty red, frequently washed with white: 19
  • Upper parts mahogany brown washed with white: Lasiurus seminolus (Seminole bat).
19.
  • Color reddish with frosted appearance resulting from white-tipped hairs; interfemoral membrane fully haired: Lasiurus borealis (eastern red bat).
  • Color rusty-red to brownish without frosted appearance; posterior one-third of interfemoral membrane bare or only scantily haired: Lasiurus blossevillii (western red bat).
20.
  • Tragus (projection within ear) short, blunt, and curved: 21
  • Tragus long, pointed, and straight: 23
21.
22.
  • Forearm more than 32 mm; interfemoral membrane naked; color brown: Nycticeius humeralis (evening bat).
  • Forearm less than 32 mm; interfemoral membrane lightly furred on anterior third of dorsal surface; color drab to smoke gray: Pipistrellus hesperus (western pipistrelle).
23.
  • Dorsal fur tricolored when parted (black at base, wide band of light yellowish-brown in middle, tipped with slightly darker contrasting color); leading edge of wing membrane noticeably paler than rest of membrane: Pipistrellus subflavus (eastern pipistrelle).
  • Dorsal fur bicolored or unicolored with no light band in the middle; leading edge of wing same color as other parts of membrane: 24
24.
  • Calcar with well-marked keel: 25
  • Calcar without well-marked keel: 27
25.
  • Forearm more than 36 mm; foot more than 8 mm long; underside of wing furred to elbow; pelage dark brown: Myotis volans (long-legged myotis).
  • Forearm less than 36 mm; foot less than 8 mm long; underside of wing not furred to elbow; pelage light brown to buff brown: 26
26.
  • Hairs on back with dull reddish-brown tips; black mask not noticeable; thumb less than 4 mm long; naked part of snout about as long as the width of the nostrils when viewed from above: Myotis californicus (California myotis).
  • Fur on back with long, glossy, brownish tips; black mask usually noticeable; thumb less than 4 mm long; naked part of snout approximately 1.5 times the width of the nostrils: Myotis ciliolabrum (western small-footed myotis).
27.
  • Forearm more than 40 mm: 28
  • Forearm usually less than 40 mm: 29
28.
  • Conspicuous fringe of stiff hairs on free edge of interfemoral membrane: Myotis thysanodes (fringed myotis).
  • No conspicuous fringe of stiff hairs on free edge of interfemoral membrane: Myotis velifer (cave myotis).
29.
  • In Texas occurring west of 100th meridian: 30
  • In Texas occurring east of 100th meridian: 31
30.
  • Dorsal fur usually with a slight sheen; forearm more than 36 mm; total length more than 80 mm: Myotis lucifugus (little brown myotis).
  • Dorsal fur usually lacking a sheen; forearm less than 36 mm; total length less than 80 mm: Myotis yumanensis (Yuma myotis).
31.
  • Ear more than 16 mm, extending more than 2 mm beyond nose when laid forward; tragus long (9-10 mm), thin, and somewhat sickle-shaped: Myotis septentrionalis (northern myotis).
  • Ear less than 16 mm, not extending more than 2 mm beyond nose when laid forward; tragus shorter and straight: Myotis austroriparius (southeastern myotis).