Chrotopterus auritus - Big-eared Wooly Bat​

Physical Description:

Chrotopterus auritus is one of the largest microchiropterans with only three new world phyllostomids (Phylloderma stenops, Phyllostomus hastatus, and Vampyrum spectrum) comparing in size.   C. auritus can be distinguished from these three by having darker pelage, dorsal hair that is twice as long (12 mm), and longer ears (>40 mm) (Medellin 1989). 

The skull features a wide rostrum with well developed canines and upper incisors, and strong lower molars featuring w-shaped lophs.  The mandible bears canines that extend beyond the lower incisors.  Of the lower premolars, only the first and third are well developed. The dental formula is I 2/1, C 1/1, P 2/3, M 3/3.  The braincase is inflated and elongated with a prominent sagittal crest (Medellin 1989). 

The fur is wooly, blackish gray or brown.  The forearm measures 76-80 mm and features a thumb with large, long, curved claws.  The wings are wide and feature whitish tips.  The uropotagium is wide and totally encloses the short tail.  The ears are large, rounded and unconnected.  The nose leaf is broad, thick ribbed, and rather blunt with a well-developed lower element.  The lower lip features two pads, forming a v-shaped groove (Medellin 1989).  Males can be distinguished from females by an enlarged glandular throat pouch (Redford and Eisenberg 1992).    

Distribution:

C. auritus range extends from southern Mexico, throughout Central America and northern South America, Brazil, Bolivia, Peru, Paraguay and into northern Argentina (Redford and Eisenberg 1992).  The distribution within Paraguay seems to be limited to the central region of the country (Willig et al. 2000).  C. auritus inhabits tropical rainforests, tropical deciduous forests, and cloud forests (Medellin 1989). 

Ontogeny and Reproduction:

Litter size is typically one, born after a 100 day gestation period (Redford and Eisenberg 1992).  Female reproductive cycles are most likely monstrous with geographic variability.  Reproductive females have been captured between the months of April and July, and males with scrotal testes have been recorded during the month of July (Medellin 1989).

Ecology and Behavior:

C. auritus is an opportunistic carnivore, preying on food items ranging from birds, bats, and small mammals (Medellin 1988; Sazima 1978) to reptiles (Tuttle 1967) and large insects (Medellin 1989). Bonato et al. (2004) has determined that 61-73% of prey consisted of small vertebrates.  Feeding behavior is typically perch hunting with an average hunting territory of 4 ha (Brooke 1988).  Nasally emitted audible cues are used to locate prey (Medellin 1989), with the bat typically losing interest if prospective prey stops movement (Medellin 1988).  Prey is captured by wrapping the wings around the body, and digging in with the thumbs.  After capture, prey is killed by several swift bites to the nape of the neck or top of the head.  Prey is then carried to a perch where it is consumed from the head downward, with the bat often using its wing as a sort of platter to support the carcass (Medellin 1988).

C. auritus inhabits tropical rainforests, tropical deciduous forests, and cloud forests (Medellin 1989).  Roost sites are typically near the entrance of caves (Redford and Eisenberg 1992), or hollow trees (Medellin 1988).  Roost sites have also been identified in Mayan ruins (Rick 1968).  Colonies are typically small, ranging between two and seven individuals.  Other bat species are rarely found roosting near a colony of C. auritus, but the species is normally associated with areas of high bat diversity.

Remarks:

Opossums were at one time valued for their fur, which was used to make cuffs and collars for jackets and coats.  They are still trapped by some and eaten although they are not regarded as a prime source of nutrition.  They are hunted primarily in the southern U.S. at night with the aide of hounds and spotlights (Lyon 1936).

Literature Cited:

Bonato, V., K. Gomes-Facure and W. Uieda. 2004. Food habits of the subfamily Vampyrinae in Brazil. Journal of Mammalogy 85(4):708-713     

Brooke, A. P.  1988.  Prey selection, foraging and habitat use by Chrotopterus auritus in Costa Rica.  Bat Research News  29(4): 44. 

Medellin, R. A. 1988. Prey of Chrotopterus auritus, with notes on feeding behavior. Journal of Mammalogy 69(4) 841-844

Medellin, R. A. 1989. Mammalian Species No. 343. The American Society of  Mammalogists.  5 pp.

Redford, K. H and J. F. Eisenberg. 1992. Mammals of the Neotropics: The Southern Cone.  University of Chicago Press.  Vol 2.

Rick, A. M. 1968. Notes on bats from Tikal, Guatemala.  Journal of Mammalogy 49:516-520

Sazima, I. 1978. Vertebrates as food items of the false wooly vampire bat, Chrotopterus auritus. Journal of Mammalogy  59(3):617-618.   

Tuttle, M. D. 1967. Predation by Chrotopterus auritus on geckos.  Journal of Mammology  48(2):319.

Willig, M. R., S. J. Presley, R. D. Owen and C. Lopez-Gonzalez.  2000.  Composition and structure of bat assemblages in Paraguay: A subtropical-temperate interface. Journal of Mammalogy  81(2):386-401   

Reference written by Erik Blomberg, Biol 378 (Mammalogy), University of Wisconsin – Stevens Point:  Edited by Kim Moore. Page last updated 12-15-04.