Chrotopterus auritus
big-eared woolly bat

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

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)

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)

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

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)

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)

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)

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)

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

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

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

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)