More Information

Additional Information

Microgale dryastree shrew tenrec

By Heather Gillespie

Geographic Range

Tree shrew tenrecs, Microgale dryas, have only been found at the Ambatovaky Special Reserve in north-eastern Madagascar. Ambatovaky is a nature reserve located 50km west of the town Soanierana-Ivongo on the eastern coast of Madagascar. ("International Union for Conservation of Nature and Natural Resources", 2003; Crowley, 2001; Garbutt, 1999)

Habitat

M. dryas lives only in the tropical rainforest of north-eastern Madagascar. This region includes dense vegetation (mainly evergreen forests). The area is characterized having sharp-peaked mountains and some aquatic elements because of the presence of two relatively large rivers. M. dryas is solely terrestrial and occupies this dense habitat. (Crowley, 2001; Garbutt, 1999; Goodman and Benstead, 2004)

  • Range elevation
    0 to 2300 m
    0.00 to 7545.93 ft

Physical Description

Like other members of the genus Microgale, M. dryas is shrew-like in appearance. Its pelage is soft, short, and dense. It ranges in length from 170 to 180 mm, and weighs an average of 40 g. It is somewhat smaller than closely related species like M. dobsoni and M. gracilis. Microgale dryas can be distinguished from these species by its relatively short, grey tail and its distinctive pelage. The ventral pattern is generally reddish- or grey-brown. The dorsal pattern is unique because the guard hairs are long, with the mid-region of each hair flat and broad. (Garbutt, 1999; Goodman and Benstead, 2004)

  • Sexual Dimorphism
  • sexes alike
  • Average mass
    40 g
    1.41 oz
  • Range length
    170 to 180 mm
    6.69 to 7.09 in

Reproduction

Reproductive and mating behavior of M. dryas is not well known. In other members of the genus, males and females may have stable relationships. Microgale dobsoni males and females associate with one another throught the year, and may be monogamous. (Nowak, 1999)

Although specific information about general reproductive behavior of M. dryas is unknown, the reproductive behaviors of other members of the genus Microgale are described below.

Reproduction generally begins with the onset of the rainy season in north-eastern Madagascar in September. Pregnancy lasts 2 to 3 months, and litters are generally born in November. There are generally between 1 and 4 offspring per litter. Females reproduce no more than twice in one year.

In M. talazaci, neonates weigh an average of 3.6 g. These young are weaned at about one month of age. Sexual maturity occurs at 21 months of age.

It is likely that M. dryas is like other members of the genus in these parameters. (Grzimek, 2003)

  • Breeding interval
    Tree shrew tenrecs probably reproduce 1 to 2 times per year.
  • Breeding season
    Matingin the genus Microgale usually occurs in September or October
  • Range number of offspring
    1 to 4
  • Range gestation period
    2 to 4 months
  • Average weaning age
    1 months

The specific parental investment and care patterns for M. dryas are not known. Information from related species in the same genus indicates that parental investment is similar to that of true shrews, Soricidae. Offspring are relatively helpless and remain in a nest guarded by the mother for about a month. Females of this genus care for the offspring, providing milk, grooming, and protection. The role of males in parental care has not been documented. (Grzimek, 2003; Grzimek, 2003; Grzimek, 2003)

  • Parental Investment
  • no parental involvement
  • altricial
  • female parental care
  • pre-fertilization
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female
  • pre-independence
    • protecting
      • female

Lifespan/Longevity

The lifespan of M. dryas is not known. Members of the family Tenrecidae generally live up to 6 years in the wild. (Grzimek, 2003)

Behavior

Little is known about the behavior of M. dryas because it is rarely seen and is critically endangered. However, some behavioral traits have been observed of more common members of the genus Microgale, and these may be similar to those of M. dryas. These species tend to be terrestrial and insectivorous. They appear to be active at irregular intervals with foraging occurring during the day or at night. Some build nests for their young. They are generally solitary in the wild, and are aggressive toward unfamliar members of their species, but instances of pair-bonding have been documented in captive populations. (Garbutt, 1999; Grzimek, 2003; Nowak, 1999)

Home Range

The size of the home range of these animals is not known. However, other members of the genus are aggressive toward strangers, so it is likely that these animals are territorial. (Nowak, 1999)

Communication and Perception

Little is known about communication and perception of M. dryas, however other species of the genus Microgale have shown the following traits. They tend to have a well-developed sense of smell as well as tactile sense, especially through their whiskers (vibrissae). Some members of the genus produce a sound that may be used for communication, but sense of smell is likely the most important channel for communication. Agonism between unfamiliar individuals is a form of tactile communication. It is not known whether these animals use visual signals for communication. (Grzimek, 2003; Nowak, 1999; Wilson and Reeder, 1993)

Food Habits

M. dryas, like most other tenrecs, is primarily an insectivore. These animals consume a variety of invertebrates, including insects and arachnids. It is unknown whether M. dryas consumes plant materials or small vertebrates like its relatives in the family Tenrecidae. (Garbutt, 1999; Grzimek, 2003; Wilson and Reeder, 1993)

  • Animal Foods
  • insects
  • terrestrial non-insect arthropods

Predation

Predators of M. dryas are likely larger sized mammals, reptiles, and birds. Evidence of M. dryas was found in pellets from a Madagascar red owl. It is possible that the nocturnal behavior of M. dryas is an anti-predator adaptation. No other adaptations to avoid predation are known in this species. (Goodman and Benstead, 2004; Nowak, 1999; Wilson and Reeder, 1993)

Ecosystem Roles

The role that M. dryas has in its ecosystem is unknown. It is not a common species, and has a very restricted range. Although it acts as predator for a variety of insects, it is not known how it impacts their populations. Similarly, although it may serve as prey to a number of other animals, it is not known whether it is an important prey item for these species, or how the availability of M. dryas as a food source affects these other animals.

Economic Importance for Humans: Positive

There are no known benefits that M. dryas has on humans. Because it is so rare, it is likely that it does not affect the ecosystem or humans greatly. ("International Union for Conservation of Nature and Natural Resources", 2003)

Economic Importance for Humans: Negative

There are no known adverse affects of M. dryas on humans.

Conservation Status

The IUCN lists M. dryas as the only critically endangered member of the Tenrecidae. It has only been found in the Ambatovaky Special Reserve and is extremely rare. The ongoing major threat to this population is habitat loss due to slash and burn agriculture and destruction of the rainforests. It is listed as critically endangered because it is only found at a single location and the number of these animals is thought to be declining. ("International Union for Conservation of Nature and Natural Resources", 2003; Crowley, 2001; Garbutt, 1999; Nowak, 1999)

Contributors

Nancy Shefferly (editor), Animal Diversity Web.

Heather Gillespie (author), University of Michigan-Ann Arbor, Phil Myers (editor, instructor), Museum of Zoology, University of Michigan-Ann Arbor.

Glossary

Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

World Map

acoustic

uses sound to communicate

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

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

diurnal
  1. active during the day, 2. lasting for one day.
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.

female parental care

parental care is carried out by females

fertilization

union of egg and spermatozoan

insectivore

An animal that eats mainly insects or spiders.

island endemic

animals that live only on an island or set of islands.

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.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

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

solitary

lives alone

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.

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

2003. "International Union for Conservation of Nature and Natural Resources" (On-line). Accessed April 15, 2004 at http://www.redlist.org/search/details.php?species=13356.

Crowley, H. 2001. "Madagascar lowland forests (AT0117)" (On-line). World Wildlife Federation. Accessed April 16, 2004 at http://www.worldwildlife.org/wildworld/profiles/terrestrial/at/at0117_full.html.

Garbutt, N. 1999. Mammals of Madagascar. New Haven and London: Yale University Press.

Goodman, S., J. Benstead. 2004. The Natural History of Madagascar. Chicago and London: University of Chicago Press.

Grzimek, B. 2003. Tenrecs. Pp. 225-230 in Grzimek's Animal Life Encyclopedia: Mammals, Vol. 13, 2nd Edition. Farmington Hills: Gale Group.

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

Wilson, D., D. Reeder. 1993. Mammal Species of the World: A Taxonomic and Geographic Reference. Washington and London: Smithsonian Institution Press.

Search

Navigation Links

Information
Classification

Classification