Geogale aurita

Geographic Range

Large-eared tenrecs are endemic to the island of Madagascar and are found in the south and southwest regions of the island.

• Biogeographic Regions
• ethiopian ethiopian
  • native native

• Other Geographic Terms
• island endemic island endemic

Habitat

Geogale aurita is found widely distributed in dry, deciduous forest, gallery forests, and spiny bush in southern and southwestern Madagascar. The species has also been observed in the rainforest of the southeast. These are environments with large annual variations in rainfall.

• Habitat Regions
• tropical tropical
• terrestrial terrestrial

• Terrestrial Biomes
• forest forest
• rainforest rainforest
• scrub forest scrub forest

Physical Description

Large-eared tenrecs are small, shrew-like tenrecs with very short, soft pelage, hair-covered tails, and large pinnae. Dorsal coloration is variable, ranging from light gray to light reddish-brown. Ventrally, these animals are buffy white. Large-eared tenrecs are among the smallest living tenrecs, with wild-caught animals ranging in body mass from 5.0 to 8.5 g. The length of the head and body is 60 to 75 mm, and the total body length including the tail can be between 90 and 105 mm.

Certain characters distinguish G. aurita from other tenrecs. The dental formula is 2/2 1/1 3/2 3/3 = 34, whereas most tenrecs have 36 teeth. Furthermore, large-eared tenrecs are the only member of the family Tenrecidae that exibit postpartum oestrus, which allows females to suckle a first litter while a second litter is developing in utero.

Geogale aurita is heterothermic, and body temperatures parallel the surrounding temperature at all times of year, although body temperatures higher than ambient temperature are observed in pregnant and lactating females. Low metabolic rate is correlated with this relatively low body temperature.

Testes are abdominal in G. aurita , as they are in all other tenrecs. Members of the family Tenrecidae have a cloaca into which both the intestinal and genitourinary tracts empty.

• Other Physical Features
• endothermic endothermic
• heterothermic heterothermic
• bilateral symmetry bilateral symmetry

Reproduction

Information on the mating systems of these tenrecs was not available in the literature reviewed. Mating systems of tenrecs in general are poorly known. Most tenrecs are solitary, although some species appear to form stable long-term bonds between males and females, indicating that they may mate monogamously. It is not known at this time what mating system is employed by G. aurita .

Mating takes place from late September to March. Because these animals have a post-partum estrus, they can produce multiple litters during that time. Coital lock occurs during copulation and can last for more than 20 minutes. Large-eared tenrecs are capable of arresting the development of litters, thus the gestation period varies between 54 and 69 days. Litter size varies from 1 to 5 individuals, and the weights of the neonates range from 0.5 to 0.8 g. The offspring are altricial, and are born with closed eyes and ears. Young are weaned soon after the opening of eyes, which takes place after 21 to 33 days of age.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• fertilization fertilization
• viviparous viviparous
• embryonic diapause embryonic diapause
• post-partum estrous

Parental care in this species has not been described. However, because G. aurita is a mammal, we know that females provide extensive maternal care. Young are altricial, so it is likely that mothers provide not just food to their young, but also protection, grooming, and shelter, until the time that the young are weaned and can care for themselves. Male parental care is varied in mammals, and lacking specific information for these tenrecs, it is impossible to speculate upon.

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

Lifespan/Longevity

The lifespan of long-eared tenrecs living in the wild is unknown but in captivity they have been observed to live for more than two and a half years.

Behavior

Large-eared tenrecs are nocturnal, poor-sighted animals that depend on auditory and olfactory senses. They are mostly solitary animals, but male-female pairs are occasionally found living in proximity to each other. These animals are heterothermic and enter daily torpor. They can often be found torpid inside fallen logs and cavities of sand.

• Key Behaviors
• terricolous
• nocturnal nocturnal
• motile motile
• daily torpor
• solitary solitary

Home Range

The size of home range for these animals has not been reported, but given their small size, territories and home ranges are not likely to be very large.

Communication and Perception

Large-eared tenrecs use sound to locate their termite prey. Being a nocturnal animal with poor eyesight, G. aurita depends on auditory and olfactory senses. As in all mammals, tactile communication is important between mates as well as between mothers and their offspring. Accoustic communication between members of this species has not been reported, but may occur.

• Communication Channels
• tactile tactile
• chemical chemical

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

Large-eared tenrecs are specialized insectivores showing a clear preference for termites. Their diet consists exclusively of arthropods, which they locate by using sound. They may also show a significant preference for certain species.

• Primary Diet
• carnivore carnivore
  • insectivore insectivore

• Animal Foods
• insects

Predation

Geogale aurita is preyed upon by various groups of animals. Remains of large-eared tenrecs have been found in pellets from two species of owls: barn owls and Madagascar long-eared owls . Other species expected to be predators of large-eared tenrecs are snakes, including Malagasy cat-eye snakes , which are associated with the habitat where Geogale is found, and carnivores such as Malagasy narrow-striped mongooses .

Ecosystem Roles

Large-eared tenrecs are specialized termites feeders and thus act as secondary consumers in an ecosystem. The species also provides feeding opportunities for consumers at higher trophic levels.

Economic Importance for Humans: Positive

Habitats populated by large-eared tenrecs are not densely populated by humans, thus no known specific economic influence on human societies is known.

Economic Importance for Humans: Negative

Large-eared tenrecs have no known specific economic influence on human societies.

Conservation Status

Large-eared tenrecs do not appear to be threatened, but as they are dependent on forest habitats, their distribution may decrease with increasing loss of suitable habitats. Other threats are indirect effects due to increased use of pesticides. Geogale aurita is a specialized termite feeder and termites are affected by pesticides. Thus, the potential effect on G. aurita appears high.

Other Comments

Geogale has traditionally been placed in the monotypic subfamily Geogalinae . An African origin of tenrecs is widely accepted. Some authorities suggest that Geogale and the other tenrecs of Madagascar share a common ancestor, and have diverged from one another after a single colonization of the island. However, there is some evidence that Geogale may not have arizen from the same colonization event that links the other tenrecs of Madagascar.

Currently G. aurita is considered the sistergroup of the remaining tenrecs, and it is the only living descendent along its branch; the remaining Malagasy species are descendents of the other branch.

Due to dental similarities to Geogale in a fossil found in Miocene deposits of Kenya, this fossil was originally placed in Geogale . These dental similarities were considered too specialized to give rise to the remaining tenrecs, thus the ancestor of Geogale must have had colonized Madagascar independently.

The identification of this fossil has since been disputed, and is now taxonomically placed as Parageogale . The phylogenetic relationship to other members of the family Tenrecidae remains uncertain, but molecular and morphological evidence suggests a sister relationship, thus supporting a two colonizations hypothesis.

Additional Links

Encyclopedia of Life

Contributors

Thomas Nielsen (author), University of Alaska Fairbanks, Link E. Olson (editor, instructor), University of Alaska Fairbanks.

Nancy Shefferly (editor), Animal Diversity Web.

References

Goodman, S., O. Langrand, C. Raxworthy. 1993. Food habits of the Madagascar long-eared owl Asio madagascariensis in two habitats in southern Madagascar. Ostritch , 64: 79-85.

Goodman, S., O. Langrand, C. Raxworthy. 1993. The food habits of the barn owl Tyto alba at three sites on Madagascar. Ostritch , 64: 160-171.

Nowak, R. 1999. Walker's Mammals of the World, Sixth Edition . Baltimore and London: The Johns Hopkins University Press.

Olson, L., S. Goodman. 2003. Phylogeny and biogeography of tenrecs. Pp. 1235-1242 in The Natural History of Madagascar . Chicago and London: The University of Chicago Press.

Peveling, R., A. McWilliam, P. Nagel, H. Rasolomanana, Raholijaona, L. Rakotomianina, A. Ravoninjatovo, C. Dewhurst, G. Gibson, S. Rafanomezana, C. Tingle. 2003. Impact on locust control on harvester termites and endemic vertebrate predators in Madagascar. Journal of Applied Ecology , 40: 729-741.

Poduschka, W., C. Poduschka. 1985. Zur frage des gattungsnamens von "<<Geogale" aletris>> Butler und Hopwood 1957 *<<Mammalia>>: <<Insectivora>>) aus dem Miozän Ostafrikas . Zeitschrift fur Säugertierkunde , 50: 129-140.

Stephenson, P. 2003. Lipotyphla (Insectivora): Geogale aurita , Large-eared Tenrec. Pp. 1265-1267 in The Natural History of Madagascar . Chicago and London: The University of Chicago Press.

Tingle, C., J. Rother, C. Dewhurst, S. Lauer, W. King. 2000. "Pesticide Action Network" (On-line pdf). Accessed December 02, 2004 at http://www.pan-uk.org/briefing/fipronil.pdf .