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Chrotopterus auritusbig-eared woolly bat

By Kelly Houseal

Geographic Range

Chrotopterus auritus occur in southern Mexico, through Central America, and into northern Argentina. (Nowalk, 1994)

Habitat

Big-eared woolly bats tend to live near streams and other moist areas in forested lowlands, tropical rainforests, tropical deciduous forests, and cloud forests. They have been reported to roost in hollow trees, caves, and even Mayan ruins. (Medellin, 1989; Nowalk, 1994)

  • Other Habitat Features
  • caves
  • Range elevation
    0 to 2000 m
    0.00 to 6561.68 ft

Physical Description

Big-eared woolly bats are large bats in the New World phyllostomid group which includes Phyllostomus hastatus, Phylloderma stenops, and Vampyrum spectrum, the only other bats similar in size. Big-eared woolly bats range from 100 to 112 mm in length with males weighing about 72.7 g and females about 90.5 g. Males also have large glands, often located on the middle of the upper chest, which release scents that serve as sexual identifiers. Females occassionally have these glands as well, but they release no scent. Wings of C. auritus are elliptical in outline with pointed tips and a high wing loading which makes them more maneuverable. The forearm is about 75 to 87 mm in length. Additionally, their tails are very short, with a length of 7 to 17 mm. (Kunz and Racy, 1998; Medellin, 1989; Nowalk, 1994; Wimsatt, 1970)

Big-eared woolly bats have long (12 mm), soft, dark brown hair on their upper parts and shorter, paler, grayish brown hair on its lower parts. The front of the neck has a small glandular pocket similar to many other species of bats. Their heads are robust, with a wide rostrum and large, separate, ovate ears. They have smooth lips and chin except for a small wart on the center of the lower lip and small elevations on either side of the lips. They have six incisors: four on the top and two on the bottom. The regular W shape pattern of molars in bats is modified on the upper molars. They also have large, curved claws as well as long thumbs used to latch the wings together around prey. (Hill and Smith, 1984; Medellin, 1989; Nowalk, 1994; Wimsatt, 1970)

  • Sexual Dimorphism
  • female larger
  • Range mass
    75 to 96 g
    2.64 to 3.38 oz
  • Range length
    100 to 112 mm
    3.94 to 4.41 in

Reproduction

There is little known about the mating system of C. auritus, although it is thought that C. auritus breed and raise a single young before they breed again. It is also not known if C. auritus is polygamous or monogamous, but many other tropical bat species in the family Phyllostomidae form monogamous groups. The time span that these family units remain together is unknown. (Altringham, 1996; Hill and Smith, 1984)

Big-eared woolly bats have low reproduction rates, typically having just one offspring per litter. Females have only been reported to be reproductively active during the second half of the year. Pregnant females, however, have been observed from April until July. This is consistent with a monestrous cycle, varying geographically. One female taken into captivity gave birth to a single young after 99 days. They have a maximum gestation period of 220 days and a maximum weaning time of nine months. The age of reproductive maturity is between one and two years. (Kunz and Racy, 1998; Medellin, 1989; Nowalk, 1994)

  • Breeding interval
    Chrotopterus auritus generally have only one offspring per year.
  • Breeding season
    Females are reproductively active only during the second half of the year, but it can vary due to geographical differences. Pregnant females have been observed from April until July.
  • Average number of offspring
    1
  • Range gestation period
    220 (high) days
  • Range weaning age
    9 (high) months
  • Range age at sexual or reproductive maturity (female)
    1 to 2 years
  • Range age at sexual or reproductive maturity (male)
    1 to 2 years

It is thought that C. auritus take care of their young until they are able to survive on their own. Care and feeding of young bats is almost entirely the mother’s responsibility. Soon after birth the infant bat attaches to one of the mother’s pectoral mammae and is carried in that position for a week or two, depending on the size of the infant. The mother continues to provide for her pup through weaning and occasionally longer. (Altringham, 1996; Hill and Smith, 1984)

  • Parental Investment
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female

Lifespan/Longevity

It is not known how long C. auritus live in the wild or in captivity.

Behavior

Big-eared woolly bats exist in low population density areas and form complex social groups that tend to stay together for several years. Colonies can consist of one to seven individuals, but typically contain three to five individuals. (Hill and Smith, 1984; Kunz and Racy, 1998; Medellin, 1989; Nowalk, 1994)

Big-eared woolly bats tend to be most active at night, during which time their internal body temperature is about 37 to 39 °C. The body temperature may drop 2 to 3 °C when the bat is not active during the day. An internal body temperature of less then 20 °C may be fatal for the bat. Big-eared woolly bats exposed to a constant temperature between 26 and 27 °C rarely have their internal body temperature fall below 32 °C. Therefore, they are homoeothermic over a wide range of temperatures. (Altringham, 1996; Hill and Smith, 1984; Wimsatt, 1970)

Home Range

There is no information available on the home range of Chrotopterus auritus. (Nowalk, 1994)

Communication and Perception

Little is known about the communication for C. auritus. However, bats in the suborder Microchiroptera,to which C. auritus belongs, use echolocation, in which high-frequency sounds are emitted to communicate and “see." Members of the Phyllostomidae family emit low intensity pulses. Bats will typically emit sounds through their nose or mouth. In the case of C. auritus, it would be more likely that the sounds come out of their mouth due to their small nose size. The signals are not emitted in all directions; little can be sensed behind, above, or below the bat. When the bats receive the frequencies back they can rotate their ears to better hear the sound. Mother bats and infants also communicate using sound and smell, starting shortly after birth. Mothers can identify the vocalization of their infant among many calling newborns. (Hill and Smith, 1984; Novic, 1969; Wimsatt, 1977)

Food Habits

Big-eared woolly bats are not exclusively carnivores. In fact, they have a flexible foraging strategy that allows them to eat insects and fruit in addition to extensive consumption of small vertebrates like bats, opossums, mice, birds, lizards, and frogs. Big-eared woolly bats have a diet similar to that of Vampyrum spectrum and Trachops cirrhosus. Big-eared woolly bats have significant seasonal diet changes. In the wet season they eat more insects because they are more abundant. However, age and sex do not have any effect on what they eat. (Altringham, 1996; Hill and Smith, 1984; Kunz and Racy, 1998)

Big-eared woolly bats use audible cues to help them locate prey as well as other bats. When prey does not move, it is hard for the bat to locate it and thus it loses interest in the prey. The bat wraps its wings around the prey and locks its thumbs together. The bat will then kill the prey with a few quick bites to the throat, if eating a bat or mouse, or the top of the head, if eating a bird. When the prey is dead, the bat will fly to a perch and eat its food usually starting from the head and working its way down. Hard to digest objects such as beaks, feathers, tails, back skin, stomachs, intestines, and wings are rejected by the bat. It can take one to 20 hours for a bat to eat its meal. (Medellin, 1989; Wimsatt, 1977)

  • Animal Foods
  • birds
  • mammals
  • amphibians
  • reptiles
  • insects
  • Plant Foods
  • fruit

Predation

There are no known predators of big-eared woolly bats nor any recorded cases of natural death. Most bats are preyed on by owls (Strigiformes) in flight or by snakes (Serpentes) from roosts. (Medellin, 1989)

Ecosystem Roles

Big-eared woolly bats help to disperse seeds. They also help to keep insect populations under control. (Medellin, 1989)

  • Ecosystem Impact
  • disperses seeds
  • pollinates

Economic Importance for Humans: Positive

Big-eared woolly bats contribute to insect control, lowering the need for insecticides. This saves money and decreases the use of toxins.

  • Positive Impacts
  • controls pest population

Economic Importance for Humans: Negative

Big-eared woolly bats have no known negative impact on humans.

Conservation Status

Big-eared woolly bats are not endangered but deforestation is reducing the area they can live in and may prove to be a problem in future years. (Kunz and Racy, 1998)

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Kelly Houseal (author), Kalamazoo College, Ann Fraser (editor, instructor), Kalamazoo College.

Glossary

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

acoustic

uses sound to communicate

arboreal

Referring to an animal that lives in trees; tree-climbing.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

crepuscular

active at dawn and dusk

echolocation

The process by which an animal locates itself with respect to other animals and objects by emitting sound waves and sensing the pattern of the reflected sound waves.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

insectivore

An animal that eats mainly insects or spiders.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

tactile

uses touch to communicate

terrestrial

Living on the ground.

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

ultrasound

uses sound above the range of human hearing for either navigation or communication or both

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

References

Altringham, J. 1996. Bats: Biology and Behavior. New York: Oxford University Press Inc..

Hill, J., J. Smith. 1984. Bats: A Natural History. United Stated of America: British Museum (Natural History) and University of Texas Press, Austin.

Kunz, T., P. Racy. 1998. Bat Biology and Conservation. Washington: Smithsonian Institute Press.

Medellin, R. 1989. Chrotopterus auritus. Mammilian Species, 343: 1 - 5.

Medellin, R. 1988. Prey of Chrotopterus Auritus, with Notes on Feeding Behavior. Journal of Mamology, 69/4: 841 - 4.

Novic, A. 1969. The World of Bats. Switzerland: Holt, Rinehart, and Winston, Inc..

Nowalk, R. 1994. Walker's bats of the World. United States of America: John Hopkins University Press.

Wimsatt, W. 1970. Biology of Bats, Volume I. New York: Academic Press Inc..

Wimsatt, W. 1977. Biology of Bats, Volume II. New York: Academic Press Inc..

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