Sac-winged bats, sheath-tailed bats, and ghost bats

(Emballonuridae)

Class Mammalia

Order Chiroptera

Suborder Microchiroptera

Family Emballonuridae

Thumbnail description
Small, insect-feeding bats with mostly brown or gray fur and relatively large eyes; many emballonurid bats roost at almost vertical substrates with the folded forearms supporting the body

Size
Head and body length: 1.4–6.3 in (36–160 mm); forearm: 1.4–3.9 in (36–100 mm); weight:0.1–3.5 oz (3–100 g)

Number of genera, species
12 genera, 47 species

Habitat
Daytime roosts in well-lit portions of hollow trees, buttress cavities, rock shelters, or caves. Foraging habitats in evergreen forests, semideciduous forests, or savannas

Conservation status
Critically Endangered: 2 species; Endangered: 2 species; Vulnerable: 10 species; Lower Risk/Near Threatened: 7 species

Distribution
In tropical and subtropical regions from Mexico to Argentina in the New World. In the Old World in Africa, Madagascar, the Indian subcontinent, and Southeast Asia to Australasia

Evolution and systematics

Emballonurid bats are first recorded in Europe from the middle Eocene to early Miocene, in Africa from early Miocene to Recent, in South and Central America from Pleistocene to Recent, and in other areas of their geographical range from Recent. Two subfamilies are distinguished: Taphozoinae and Emballonurinae. Some authors consider the genera Diclidurus and Cyttarops as a separate subfamily Diclidurinae.

Physical characteristics

Emballonurid bats are small bats with relatively large eyes. The ears have a tragus and, in some species, the ears are connected. Males of some New World species (sac-winged bats) have a sac-like organ in the frontal wing membrane that contains a strong smelling liquid. Females have only rudiments of this organ and it is not known if females use it in a behavioral context. Position and size of these sacs vary among species. The ghost bats, genus Diclidurus, have a sac-like organ in the wing-tail membrane. These bats are also an exception within the whole family as they have white fur. Within the genus Taphozous, some members possess a gland at the chest. In general, emballonurid bats have grayish to brown fur. The tail emerges free through the tail membrane and projects above its dorsal surface.

Distribution

The family Emballonuridae occurs both in the New World and in the Old World. There are 18 species in the New World with a distribution range from southern Mexico to northern Argentina. The 29 species of the Old World inhabit Africa, the Indian subcontinent, and Southeast Asia to Australasia. Most species are restricted to the lowland regions. The species diversity of emballonurid bats increases towards the equator.

Habitat

Emballonurid bats inhabit humid rainforests, seasonal semi-deciduous forests, and savannas. Most species roost in well-lit places like entries to caves and temples, at the outside of buildings, or in hollow trees and buttress cavities of large trees.

Behavior

Colonies of some emballonurid species are easily found because these bats emit social calls audible to humans. The roosting posture of emballonurid bats is characteristic as they support their body from the surface by the thumbs of the folded wings.

The social behavior of the greater sac-winged bat can be observed easily from some distance. The mating system has been described as harem-polygynous, but recent studies using molecular genetic techniques proved that harem males father only 30% of the offspring within their harems. However, harem holders have on average a higher reproductive success than non-harem males and, therefore, males benefit from defending a group of females. The courtship of male S. bilineata includes visual, acoustic, and olfactory displays. Besides a large number of social calls that have been described for this species, males emit songs that can last for up to an hour and that include many different syllables. Songs of male S. bilineata are partly in the audible range of humans. In addition to singing, males also perform hovering flights during which fragrances are fanned towards roosting females. Males possess

specialized holding sacs in the front wing membrane in which the fragrances are stored. The scents emanating from wing sacs of emballonunrid bats smell differently in different species. Histological studies proved that holding sacs of male S. bilineata and other emballonurid bats do not contain any glandular tissues. Male S. bilineata actively fill fragrances into the wing sacs each afternoon during a stereotyped behavioral sequence. During the first phase, which has been interpreted as cleaning, males swallow their urine and lick the holding

sacs intensively. After approximately 10–20 minutes of cleaning, males rest for a few minutes and then switch to a second phase. During the second phase, males press their chin onto the penis and deposit a small droplet at their chin. Afterwards, males smear this droplet into one of the holding sacs with a sideward movement of the head. This secretion probably originates from the preputial glands. Additional droplets of the gular gland are also added to the holding sacs. When transferring genital and gular secretions to the holding sacs, males alternate between the two sacs, thus refilling almost equal amounts of fragrances into both wing sacs. The second phase of perfume-blending can last up to 20–30 minutes. It is unknown if other emballonurid species with wing sacs in the male sex show a similar behavior.

Feeding ecology and diet

Emballonurid bats are aerial insectivorous bats that can be easily observed hunting for insects in a slow butterflylike flight. Larger emballonurid species, like the genus Taphozous, have a more pronounced, powerful flight. Emballonurids are among the first bats to start foraging in the evening. During periods of bad weather, some species may even start foraging in the afternoon. Occasionally, some species also glean insects from leaves. The diet of neotropical emballonurids consists mostly of small insects, primarily beetles and flies. In S. bilineata, colony members forage in an area where only they have access to. When insect abundance is declining, the whole colony moves to a different foraging site. Within foraging areas, single individuals forage in beats of 32.8–98.4 ft (10–30 m). The proboscis bat, Rhynchonycteris naso, hunts insects above or close to water surfaces. Ghost bats, genus Diclidurus, forage above the

canopy. The Old World members are similar in their diet to the New World members. The tomb bats, genus Taphozous, forage more in open spaces.

Reproductive biology

Bats of the family Emballonuridae usually give birth to a single offspring per year. Exceptions to this rule may be small species like the proboscis bat that reproduce twice each year. Most emballonurid bats show a seasonal pattern of reproduction with females giving birth to their offspring at the beginning of the rainy season. Sperm storage or delayed embryonic development occurs in some Old World members within the family Emballonuridae. The mating system varies by species.

Emballonurid bats exhibit a variety of different mating systems. Similar to other mammalian groups, polygynous mating patterns are most common. However, exceptions are for example the monogamous mating system of Cormura brevirostris and possibly also of the greater dog-faced bat, Peropteryx kappleri, and some members of the genus Taphozous. The proboscis bat is considered to have a promiscuous mating pattern. Among emballonurid bats, the greater sac-winged bat, Saccopteryx bilineata, is the best studied species.

Conservation status

The IUCN Chiroptera Specialist group lists two species as Critically Endangered (Coleura seychellensis, which is endemic to the Seychelles, and Taphozous troughtoni, of which only six specimen have ever been collected), two species as Endangered (Balantiopteryx infusca is threatened by habitat destruction and Emballonura semicaudata by development and cyclone damage), and 10 species as Vulnerable. In tropical regions, forest specialists seem to face an uncertain future if habitat destruction and forest fragmentation continues. Opportunistic species like Rhynchonycteris naso, Saccopteryx bilineata, or some species within the genus Taphozous may even live around buildings when humans do not distrub them.

Significance to humans

None known.

Species accounts

List of Species

Greater sac-winged bat

Saccopteryx bilineata

subfamily

Emballonurinae

taxonomy

Saccopteryx bilineata (Temminck, 1838), Suriname.

other common names

English: Greater white-lined bat, greater two-lined bat; German: Große Taschenflügelfledermaus, Große Sackflügelfledermaus; Spanish: Murciélago de listas.

physical characteristics

Head and body length 1.8–2.2 in (47–56 mm); forearm 1.7–1.9 in (44–48 mm); weight 0.2–0.35 oz (6–10 g). Dorsal fur dark brown with two distinct white lines and dark gray ventral fur; dark wings and tail membrane; males with wing sacs in the front wing membrane; females slightly larger than males. Saccopteryx bats turn the next to the last joint on their third fingers up rather than down when resting.

distribution

From south Mexico to southeast Brazil. From lowlands to up to 1,640 ft (500 m) in elevation.

habitat

Inhabit lowland evergreen or semi-deciduous forests and roost in well-lit portions of hollow tress, buttress cavities, and occasionally

at buildings. Colonies are divided into smaller territories in which one to nine females roost. Larger colonies can count up to 60 individuals. Each colony defends its own foraging territory, and colonies shift seasonally between different foraging habitats.

behavior

During a hovering display, males fan scents from the wing membrane towards roosting females. In addition, males emit songs to attract and retain females into their harem.

feeding ecology and diet

Feed exclusively on insects. Usually individuals emerge from the colony before sunset and hunt below the canopy along forest edges or small gaps. After dark they move higher, sometimes close to or even above the canopy. Subsequent echolocation calls alternate between 44 and 47 kHz.

reproductive biology

In Costa Rica and Panama, the mating season is restricted to a few weeks in December and January. Females give birth to a single offspring at the onset of the rainy season in July or August. In the Ecuadorian Amazon, females give birth to their offspring in December to January. Believed to be polygynous.

conservation status

Not threatened.

significance to humans

None known.

Gray sac-winged bat

Balantiopteryx plicata

subfamily

Emballonurinae

taxonomy

Balantiopteryx plicata Peters, 1867, Puntarenas, Costa Rica.

other common names

German: Graue Sackflügelfledermaus.

physical characteristics

Head and body 1.8–2.0 in (47–53 mm); forearm 1.5–1.7 in (40–45 mm); weight 0.17–0.21 oz (5–6 g). Dorsal fur pale or smoky gray, ventral fur slightly lighter gray.

distribution

Northwest Mexico to northwest Costa Rica along the Pacific slope. Additionally in some areas in east Mexico and northern Colombia.

habitat

Commonly found in deciduous forests and in areas with dry thorn scrubs.

behavior

Daytime roosts are found in caves, rock crevices, or tree hollows. Colony members perform a swarming flight around the

roost during which low frequency sounds are noticeable. These sounds are probably not produced through vocalization.

feeding ecology and diet

Feed on insects that they hunt usually above the canopy.

reproductive biology

A single pup is born at the beginning of the rainy season. Believed to be polygynous.

conservation status

Not threatened.

significance to humans

None known.

Proboscis bat

Rhynchonycteris naso

subfamily

Emballonurinae

taxonomy

Rhynchonycteris naso (Wied-Neuwied, 1820), Bahia, Brazil.

other common names

English: Long-nosed bat, sharp-nosed bat; German: Nasenfledermaus; Spanish: Murciélago de trompa.

physical characteristics

Head and body length 1.4–1.9 in (36–48 mm); forearm 1.4–1.6 in (36–40 mm); weight 0.10–0.21 oz (3–6 g). Very small bat with two wavy, faint dorsal stripes. Upperparts with grizzled, whitish fur. Nose projecting beyond mouth. Tufts of grayish hair on forearms and wing membrane. Wing and tail membrane brown.

distribution

From Veracruz, Mexico, to east Brazil, north Bolivia, and Peru. From lowlands to elevations up to 1,640 ft (500 m).

habitat

Lives close to rivers, lakes, or mangroves. Daytime roosts are found under logs, tree trunks, or branches hanging over water.

behavior

Colonies count up to 50 bats. Individuals align in vertical rows and maintain a minimum distance of approximately 3.9 in (10 cm) to the neighbor. If one approaches, the whole colony may suddenly fly off simultaneously and land in a similar place at some distance. The mating system is probably promiscuous as no pattern of association between individuals was detected in a study in Costa Rica.

feeding ecology and diet

Feed on small flies and other insects that they catch in a slow flight over water. Echolocation calls vary between 90 and 95 kHz.

reproductive biology

Polygynous. In some areas, females give birth to a single pup early in the wet season. Males have no seasonal spermatogenic pattern.

conservation status

Not threatened.

significance to humans

None known.

Greater dog-faced bat

Peropteryx kappleri

taxonomy

Peropteryx kappleri Peters, 1867, Suriname.

other common names

English: Greater doglike bat.

physical characteristics

Head and body length 2.5–2.9 in (63–75 mm); forearm 1.8–1.9 in (45–50 mm); weight 0.24–0.46 oz (7–13 g). Dorsal fur dark or reddish brown, head with distinct tuft on crown, ears black, wing and tail membrane black; males possess small sacs in the front wing membrane.

distribution

From Veracruz, Mexico, to east Brazil and Peru; from lowlands to up to 4,920 ft (1,500 m) in elevation.

habitat

Inhabits lowland evergreen forests; daytime roosts in small caves and under fallen logs within close distance to the ground.

behavior

Males sit on top of females. This roosting behavior implies a form of mate-guarding; thus, a monogamous mating system is most likely for this species. However, has also been found to roost in larger groups and not in close body contact.

feeding ecology and diet

Forage in long beats of 66–98 ft (20–30 m) in the subcanopy. The diet consists of insects. Echolocation calls vary between 30 and 35 kHz.

reproductive biology

Monogamous. A single pup is born at the beginning of the rainy season.

conservation status

Not threatened.

significance to humans

None known.

Northern ghost bat

Diclidurus albus

subfamily

Emballonurinae

taxonomy

Diclidurus albus Wied-Neuwied, 1820, Bahia, Brazil.

other common names

English: White bat, jumbie bat; German: Geisterfledermaus, Weisse fledermaus; Spanish: Murciélago blanco, murciélago albino.

physical characteristics

Head and body length 2.7–3.2 in (68–82 mm); forearm 2.4–3.6 in (63–93 mm); weight 0.6–0.8 oz (17–24 g). Large white bat with yellowish ears; grayish hair bases may be visible; ears short and rounded; tail membrane with single brown sac close to the tip of the tail.

distribution

From Nayarit, Mexico, to east Brazil and north Peru; from lowland to montane areas up to 4,920 ft (1,500 m).

habitat

Daytime roosts consist of small groups or single individuals under palm fronds.

behavior

The social behavior of this bat is virtually unknown.

feeding ecology and diet

Forage in the open space above the canopy. Occasionally, these bats are attracted insects swarming around street lamps. Echolocation calls vary between 22 and 25 kHz.

reproductive biology

Nothing is known. The reproductive biology of this species has not yet been studied.

conservation status

Not threatened.

significance to humans

None known.

Lesser sheath-tailed bat

Emballonura monticola

subfamily

Emballonurinae

taxonomy

Emballonura monticola Temminck, 1838, Java, Indonesia.

other common names

None known.

physical characteristics

Head and body length 1.6–1.8 in (40–45 mm); forearm 1.7–1.8 in (43–45 mm); weight 0.14–0.17 oz (4–5 g). Fur dark brown to reddish brown, wing and tail membrane black; large eyes.

distribution

Malay Peninsula, including south Myanmar and Thailand, Sumatra, Java, Banka, Billiton, Engano, Babi, Anamba, Batu, Nias, Mentawi, Borneo, Sulawesi, and Karimata.

habitat

Inhabits forests; daytime roosts may be found at exposed sites like hollow logs, caves, or rock shelters.

behavior

Sizes of daytime roosts range from two to 20 individuals. However, larger colonies with up to 100–150 bats have also been found in caves.

feeding ecology and diet

Hunts small insects in dense forests. This species has also been observed to forage during the day in dense shade.

reproductive biology

Observations indicate two birth periods per year in Malay Peninsula in February–March and October–November; females give birth to a single young during each birth period. Believed to be polygynous.

conservation status

Not threatened.

significance to humans

None known.

Mauritian tomb bat

Taphozous mauritianus

subfamily

Taphozoinae

taxonomy

Taphozous mauritianus Geoffroy, 1818, Mauritius.

other common names

German: Mauritius Grabfledermaus.

physical characteristics

Head and body length 2.9–3.6 in (75–93 mm); forearm 2.3–2.5 in (58–65 mm); weight 0.7–1.3 oz (20–36 g). Dorsal fur brownish gray speckled with white; ventral side almost pure white. Both sexes may have a throat pocket. In Nigeria and Mozambique, this pocket is present only in males, whereas it can be found in both sexes in Sudan (although more pronounced in the male sex). In West Africa, males have a functioning sac and females have a vestigial pouch.

distribution

Sub-Saharan Africa, Madagascar, Mauritius, Assumption Island, Aldabra Island, and Reunion.

habitat

Daytime roosts in tree trunks, rock faces, or the external walls of buildings. Predominantly open savanna, sometimes semi-deciduous forests.

behavior

Initially discovered in ancient Egyptian tombs by the scientists who accompanied Napoleon on his campaign. The name tomb bat is basically unjustified, because these animals are not generally associated with tombs. Daytime roosts are found in rather open spaces that are occasionally penetrated by daylight, such as underneath roofs or on walls. In colonies, individuals roost as pairs in close association. Individuals move quickly sideways or upwards when disturbed.

feeding ecology and diet

A fast aerial hunter of insects, mostly moths. A long-range feeding strategy has been observed.

reproductive biology

Monestrous in some areas of its distribution range and polyestrous in others. Most likely polygynous.

conservation status

Not threatened.

significance to humans

None known.

Resources

Books

Eisenberg, J. F. Mammals of the Neotropics 1. The Northern Neotropics. Chicago and London: The University of Chicago Press, 1989.

Eisenberg, J. F., and K. H. Redford. Mammals of the Neotropics 3. The Central Neotropics. Chicago and London: The University of Chicago Press, 1999.

Emmons, L. H. Neotropical Rainforest Mammals—A Field Guide. Chicago and London: The University of Chicago Press, 1990.

Hutson, A. M., S. P. Mickleburgh, and P. A. Racey. Global Status Survey and Conservation Plan—Microchiropteran Bats. IUCN/SSC Chiroptera Specialist Group. Gland, Switzerland, and Cambridge, UK: IUCN Publications, 2001.

Kingdon, J. East African Mammals. Chicago and London: The University of Chicago Press, 1984.

Reid, F. A. A Field Guide to the Mammals of Central America and Southeast Mexico. New York and Oxford: Oxford University Press, 1997.

Nowak, R. M. Walker's Mammals of the World. 5th ed. Baltimore and London: The Johns Hopkins University Press, 1991.

Voigt C. C., G. Heckel, and O. von Helversen. "Conflicts and Strategies in the Mating System of the Sac-winged Bat." In Functional and Evolutionary Ecology of Bats, edited by G. F. McCracken, A. Zubaid, and T. H. Kunz. Oxford: Oxford University Press, 2003.

Periodicals

Bradbury, J. W., and L. Emmons. "Social Organization of some Trinidad bats. I. Emballonuridae." Zeitschrift für Tierpsychologie 36 (1974): 137.

Bradbury, J. W., and S. L. Vehrencamp. "Social Organization and Foraging in Emballonurid Bats. I. Field Studies." Behavioural Ecology and Sociobiology 1 (1976): 337.

——. "Social Organization and Foraging in Emballonurid Bats. III. Mating Systems." Behavioural Ecology and Sociobiology 2 (1977): 1.

Heckel, G., C. C. Voigt, F. Mayer, and O. von Helversen. "Extra-harem Paternity in the White-lined Bat Saccopteryx bilineata." Behaviour 136 (1999): 1173.

Voigt, C. C. "Individual Variation of Perfume-blending in Male Sac-winged Bats." Animal Behaviour 63 (2002): 907.

Voigt, C. C., and O. von Helversen. "Storage and Display of Odor by Male Saccopteryx bilineata (Chiroptera; Emballonuridae)." Behavioral Ecology and Sociobiology 47 (1999): 29.

Christian C. Voigt, PhD