Smoky bats

(Furipteridae)

Class Mammalia

Order Chiroptera

Suborder Microchiroptera

Family Furipteridae

Thumbnail description
Tiny coarse-furred bats with short, broad, dish-like ears, reduced eyes, a short upturned snout, a vestigial thumb, and functionless wing claw

Size
Head and body length 1.4–2.6 in (3.5–5.8 cm); tail 0.9–1.4; in (2.4–3.6 cm); forearm 1.8–1.6 in (3.0–4.0 cm); 0.1 oz (3 g). Females are lightly larger than males

Number of genera, species
2 genera; 2 species

Habitat
Amorphochilus is known from isolated populations in dryland coastal forests; Furipterus prefers moist lowland tropical rainforests below 492 ft (150 m)

Conservation status
Vulnerable: 1 species

Distribution
Central and South America

Evolution and systematics

There are no known fossils of this bat family. Belonging to the superfamily Vespertilionoidea, they are probably most closely related to Central and South American disk-winged bats (Thyropteridae), funnel-eared bats (Natalidae), and the New World sucker-footed bat (Thyropteridae).

Physical characteristics

Among the smallest Neotropical bats, furipterids have a delicate appearance. The broad wings are long for the body, an adaptation for a fluttering flight. This is aided by a well-developed uropatigium, which is stiffened by a long tail that does not reach the tail membrane's trailing edge. The translucent uropatigium bears transverse lines. The skull is distorted into a helmet-like shape to accommodate the enlarged ears. Dish-shaped, the ears enclose the eyes and extend almost to the lower jawline. The pig-like snout is short and upturned at the tip. There is no nose leaf. The tiny eyes are nearly hidden by fur. A thumb is present, but is so small as to be invisible. It is enclosed in the wing membrane and only a small functionless claw protrudes. The legs and feet are short and weak, but the claws are powerful. The two genera are best told apart by the presence of pronounced wart-like outgrowths around the mouth and lips in Amorphochilus. In the field, confusion is unlikely since the ranges of the two genera do not overlap and the physical characteristics of the family are unmistakable. The family name means "winged furies," and comes from hideous avenging deities of Greek mythology. Why this small inoffensive bat should excite such contempt is unknown.

Distribution

Amorphochilus occurs west of the Andes, and is known from a number of scattered and isolated sites from central coastal Ecuador south to northern Chile. Furipterus has a much broader and continuous distribution, occurring from Costa Rica through lowland Brazil and Peru. It is also found in Trinidad.

Habitat

Of the two species, Amorphochilus appears to have the broader habitat tolerances. It has been recorded in a number of different vegetation types, ranging from primary forest to semidesert brush and cultivated land. Furipterus either prefers or requires primary lowland moist forest.

Behavior

The great aerial agility of furipterids means they easily avoid mist nets. With spotty distributions and a small number of museum specimens, these bats have a reputation for being rare and difficult to study. This means little is known about them. Most information comes from studies of their roosts. Both Amorphochilus and Furipterus roost colonially. Up to 300 animals have been found roosting together.

Feeding ecology and diet

Furipterids mostly hunt small moths within the forest undergrowth. Such hunting requires both agility and low flight speeds. This is achieved with wings that are both broad (a low stalling speed) and proportionately long (smaller turning circle). Both are assisted by a well-developed uropatigium that allows for a low stalling speed and slow flight.

Reproductive biology

Little is known. Like other bats, female bears a single young one. Unusual among bats, furipterid nipples are positioned abdominally. As a result, the young position themselves head-up on the head-down roosting mother.

Conservation status

The IUCN considers Amorphochilus to be Vulnerable. Furipterus is not currently thought to be in danger.

Significance to humans

None known, beyond the usual insect-removal services provided by any small insectivorous chiropteran. No known legends or religious significance.

Species accounts

List of Species

Smoky bat

Furipterus horrens

taxonomy

Furia horrens (F. Cuvier, 1828), Mana River, French Guiana. In Latin, horrens means "bristle," and, indeed, its muzzle is very bristly.

other common names

English: Thumbless bat, lesser thumbless bat.

physical characteristics

The smaller of the two species in this family, it is one of the smallest bats in the Neotropics. Females are significantly larger than males by 10–15%. Body fur is dense, with the fur on the head especially long and thick, enough to almost conceal the mouth. Color of the back varies from fine slate blue to brownish gray, with a paler belly. The ears are dark and stiff, and the snout is black.

distribution

Costa Rica to southern Brazil, including Venezuela and Colombia, but not west of the Andes. Also on Trinidad, but no other Caribbean islands.

habitat

Most commonly collected in humid lowland rainforest, often near streams. However, some have been netted in village clearings.

behavior

Roosts of have been found in caves, hollow trees, and in or beneath fallen rotting logs, all inside forest. Though poorly known and infrequently encountered, studies in French Guiana suggest they can be quite commonly found if roost sites are searched for. It has a wide distribution and is probably more retiring than rare.

feeding ecology and diet

Has been observed foraging over the forest floor at heights of 3.2–16.4 ft (1–5 m). The recorded diet consisted solely of small moths. Individuals leave the roost only when darkness is complete.

reproductive biology

Roosting aggregations are mostly mixed sex, but all-male groups have been found, suggesting that females may use special sites for raising young. Mating system is not known.

conservation status

Not threatened.

significance to humans

None known.

Schnabeli's thumbless bat

Amorphochilus schnablii

taxonomy

Amorphochilus schnablii Peters, 1877, Tumbes, Tumbes State, Peru.

other common names

English: Western thumbless bat, greater thumbless bat.

physical characteristics

Distinguished by the presence of warty outgrowths around the mouth. Fur of the back has a brown wash. It is slightly larger than Furipterus, and has ears that are brownish gray rather than black.

distribution

From Puna Island in the Gulf of Guayaquil, Ecuador, south through Peru to northern Chile. Probably temperature limited in southern part of range, and limited in the north by increasing moisture and rainfall.

habitat

Mostly in dry coastal forests, but occasionally inland if suitable habitat is available. Within its range area, it appears to prefer the lower seasonally deciduous rain-fed forests and avoids those forests on hilltops kept nearly perpetually moist by coastal fog. In southern Ecuador and northern Peru, it occurs in coastal oases at the mouths of rivers and in associated gallery forests.

behavior

As befits its flexible nature, it has been found roosting in many different places, including disused buildings, irrigation tunnels,

road culverts, and even a wine store. In unspoiled habitat, it has been found roosting in rock fissures.

feeding ecology and diet

There is little information. Analysis of five individuals from a colony in desert scrub at the mouth of Ecuador's Rio Javita found each stomach to contain the remains of small moths. Elsewhere, individuals have been collected whose stomachs contained both moths and small flies.

reproductive biology

Timing of birth is very restricted and appears to be timed to coincide with the onset of the local rainy season. This allows energy-stressed lactating females to forage when food is most abundant. Mating system is not known.

conservation status

Because it inhabits seasonally dry forests, it may be adapted to surviving in the hot, dry, more open habitats generally created by human action. However, it requires some type of forest cover and the IUCN expects populations to decline by 20% over the next decade due to human disturbance. It is listed as Vulnerable.

significance to humans

None known.

Resources

Books

Eisenberg, J. F., and K. H. Redford. Mammals of the Neotropics. Vol. 3, The Central Tropics: Ecuador, Peru, Bolivia, Brazil. Chicago: University of Chicago Press, 1999.

Reid, F. A. A Fieldguide to the Mammals of Central America and Southeast Mexico. Oxford: Oxford University Press, 1997.

Periodicals

Ibanez, C. "Notes on Amorphochilus schnabelii Peters (Chiroptera, Furipteridae)." Mammalia 49 (1985): 584–87.

Simmons, W., and R. S. Voss. "The Mammals of Paracou, French Guiana: A Neotropical Lowland Rainforest Fauna. Part 1. Bats." Bulletin of the American Museum of Natural History 237 (1998): 1–297.

Uieda, W., I. Sazima, and A. S. Filho. "Aspectos da Biologia do Morcego Furipterus horrens (Mammalia, Chiroptera, Furipteridae)." Revista Brasiliera do Biologia 40 (1980): 59–66.

Organizations

Bat Conservation International. P.O. Box 162603, Austin, TX 78716 USA. Phone: (512) 327-9721. Fax: (512) 327-9724. E-mail: batinfo@batcon.org Web site: <http://www.batcon.org>

Adrian A. Barnett, PhD