Microgale cowaniCowan's shrew tenrec

Geographic Range

Microgale cowani is endemic to humid forests and associated habitats in eastern Madagascar. (Jenkins, 2003; Jenkins, 2003)

Habitat

Cowan's shrew tenrecs are found in more habitats than most other shrew tenrec species. They mainly inhabit lowland humid and moist montane forests of the eastern regions. They are also known from forest patches in the eastern regions of the central highlands. A few specimens have been trapped on the edges of agricultural fields. There is no evidence of M. cowani from western Madagascar. It has been suggested that M. cowani is not well adapted to the more pronounced seasonal variation typical of western Madagascar. (Goodman and Rasolonandrasana, 2001; MacPhee, 1987)

  • Range elevation
    810 to 2450 m
    2657.48 to 8038.06 ft

Physical Description

Microgale cowani is a small, shrew-like mammal. Because there are few collected specimens and confusion over the correct classification of those specimens, descriptions of M. cowani vary. Recent reports describe it as having a soft, short, dense pelage with sparse guard hairs. There is a wide variety of coat colors and patterns, from chocolate brown with red highlights to mousy brown with larger amounts of red. They can have a darker mid-dorsal stripe and lighter bellies. Specimens in captivity noticeably darken after molting. The tail is shorter than the body and can be bi-colored like the coat. The rostrum tapers to a point and is covered with vibrissae. The eyes are small. There is a cloacae which is the outlet for evacuating waste and the reproductive organs. (Eisenberg and Gould, 1970; Jenkins, 2003; MacPhee, 1987; Racey and Stephenson, 1996; Stephenson and Racey, 1993; Stephenson, 1995)

The adult tooth formula of M. cowani is I 3/3, C 1/1, P 3/3, M 3/3. The only deciduous tooth lost before the molars erupt and are fully functional is I 3/3. The replacement of the deciduous teeth happens so rapidly it is difficult to obtain specimens showing intermediate stages of tooth loss. Deciduous and adult teeth look nearly identical, requiring expertise to tell them apart. Premolars P3 and P4 are very molariform and the canine usually has a small paraconid. (MacPhee, 1987)

All tenrecs have a lower resting metabolic rate than most other mammals. Microgale cowani has a higher resting metabolic rate, similar to tropical shrews, which is higher than most other tenrecs. The resting metabolic rate and body temperature rise for pregnant and lactating females. (Racey and Stephenson, 1996; Stephenson and Racey, 1993)

  • Sexual Dimorphism
  • sexes alike
  • Range mass
    10.0 to 13.8 g
    0.35 to 0.49 oz
  • Range length
    113 to 165 mm
    4.45 to 6.50 in
  • Average length
    131.3 mm
    5.17 in
  • Range basal metabolic rate
    23.4 mL oxygen/h to 30.4 mL oxygen/h cm3.O2/g/hr
  • Average basal metabolic rate
    27.0 mL oxygen/h cm3.O2/g/hr

Reproduction

Little is known of the mating systems of Microgale cowani. When kept in captivity, male-female pairs sometimes share a nest. (Stephenson and Racey, 1993)

Little is known about Microgale cowani reproduction. In one study 3 babies were born to captured females who had mated in the wild. Two captured specimens had 3 to 4 embryos each. Two specimens had 3 to 5 placental scars. Some specimens still had deciduous dentition so M. cowani can reproduce while still developmentally immature. (Goodman and Jenkins, 1998; Goodman, et al., 1999; Goodman, et al., 2000; Stephenson and Racey, 1993; Stephenson, 1995)

The reproduction of closely related M. dobsoni and M. talazaci were studied in the late 1960s. Three pairs of M. dobsoni were mated, resulting in one abortion and two litters of 3 young each. Four litters of M. talazaci were born in captivity, averaging 1 to 3 young. Both species started breeding after their autumn molt, around the age of 22 months. The average length of gestation was 58 to 64 days. The young started to grow hair around 12 days and opened their eyes around day 18. They grew their full coat of hair by 18 to 22 days. Around day 28 to 30 the young started following the mother at night, and were presumably weaned. (Eisenberg and Maliniak, 1985)

  • Breeding interval
    Breeding intervals are unknown in M. cowani.
  • Breeding season
    The breeding season of M. cowani is unknown.
  • Range number of offspring
    3 to 5

Not much is known about parental investment in Microgale cowani. One litter of 3 was born in captivity, but was cannibalized by the mother at 4 days of age. Like most mammals, young are likely to be cared for extensively by their female parents until they are weaned. This is supported by research on related Microgale species as well. (Stephenson and Racey, 1993)

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

Lifespan/Longevity

No data could be found for the lifespan of Microgale cowani. Two closely related species, M. dobsoni and M. talazaci were found to live up to 6 years in captivity. (Eisenberg and Maliniak, 1985)

Behavior

Microgale cowani is thought to be solitary in the wild. When male and female pairs were kept together in captivity they usually shared a nest. When two males were introduced to each other in captivity they would show defensive behavior such as mouth gaping, squealing, and biting. The offensive animal would flee for cover. The males would then often ignore each other and explore the cage. (Eisenberg and Gould, 1970; Jenkins, 2003)

When observed in the wild, Microgale cowani behaves cryptically, using all possible sources of cover and avoiding climbing. They build nests with leaves. When washing, individuals sit on their hind legs and stroke both sides of the face simultaneously with both paws, starting behind the ears and ending at the tip of the nose. The mouth is held open for washing. (Eisenberg and Gould, 1970; Jenkins, 2003)

Home Range

Little is known of the home range of Microgale cowani as they have not been extensively studied in a wild.

Communication and Perception

Microgale cowani has numerous vibrissae, which are used to sense surroundings. When two males are placed together they show agonistic behaviors such as mouth gaping, biting, and squealing. Due to the fact that Microgale cowani has not been extensively studied in the wild little else is known about how it communicates. (Jenkins, 2003)

  • Communication Channels
  • visual

Food Habits

In captivity, Microgale cowani will accept orthopteran insects, ground meat, and earthworms. There is evidence of cannibalism and eating of smaller Microgale species from traps. They forage in leaf litter and among fallen branches and tree roots on the forest floor. Prey is seized with the mouth before being consumed. (Eisenberg and Gould, 1970; Eisenberg and Maliniak, 1985; Jenkins, 2003)

  • Animal Foods
  • mammals
  • insects
  • terrestrial worms

Predation

Microgale cowani lacks obvious defenses from predators other than concealment and flight. It is possibly prey for larger reptiles, birds, and mammals. Bones of M. cowani have been found in the stomachs of Microgale pusilla, Tyto soumagnei, and Tyto alba. (Jenkins, 2003)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

Microgale cowani is a prey species to some animals and preys on arthropods. (Jenkins, 2003)

Economic Importance for Humans: Positive

Microgale cowani does not have an economic importance for humans. They are not captured for the pet trade and are too small to eat. (Raherisehena and Jenkins, 2008)

Economic Importance for Humans: Negative

Microgale cowani does not negatively affect humans.

Conservation Status

There are no known major threats to Microgale cowani. IUCN considers it to be a species of least concern as it is widely distributed, including several protected park areas, and seems to have large population numbers. It also adapts well to disturbed areas and agricultural fields. (Raherisehena and Jenkins, 2008)

Other Comments

The taxonomy of Microgale cowani has always been complicated. When the first specimens were collected it was not always clear what species they belonged to. As a result, M. cowani was incorrectly split into several species. The type specimen was collected by Thomas in 1882. Two taxonomic revisions have been undertaken, the first by MacPhee in 1987 and the second by Stephenson in 1995. Both MacPhee and Stephenson agree that M. crassipes is in fact the same species as M. cowani, but disagree about whether M. longirostris is its own species. (MacPhee, 1987; Stephenson, 1995)

Microgale cowani along with the other Microgale species is primarily studied through trapping. In areas where M. cowani is found it tends to be trapped more often than other Microgale species. This could be due to many reasons, including it being more common, or because it has specific habits that increase its susceptibility to trapping. (Goodman and Rakotondravony, 2000; Goodman and Rasolonandrasana, 2001; Goodman, et al., 2000)

Contributors

Iris Hartshorn (author), University of Alaska Fairbanks, Link Olson (editor, instructor), University of Alaska Fairbanks, Tanya Dewey (editor), Animal Diversity Web.

Glossary

Ethiopian

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

World Map

acoustic

uses sound to communicate

agricultural

living in landscapes dominated by human agriculture.

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

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

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.

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.

native range

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

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.

scrub forest

scrub forests develop in areas that experience dry seasons.

sedentary

remains in the same area

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

Eisenberg, J., E. Gould. 1970. The Tenrecs: A Study in mammalian Behavior. Washington: Smithsonian Institution Press.

Eisenberg, J., E. Maliniak. 1985. The reproduction of the genus g. Microgale in captivity. International Zoo Yearbook, 14(1): 108-110.

Goodman, S., C. Raxworthy, C. Maminirina, L. Olson. 2006. A new species of shrew tenrec (Microgale jobihely) from northern Madagascar. Journal of Zoology, 270: 384-398.

Goodman, S., P. Jenkins. 1998. The insectivores of the Reserve Speciale d'Anjanaharibe-Sud, Madagascar. A floral and faunal inventory of the Reserve Speciale d'Anjanaharibe-Sud, Madagascar: with reference to the elevational variation. Fieldiana: zoology New Series, 90: 139-161.

Goodman, S., P. Jenkins, M. Pidgeon. 1999. Lipotyphla (Tenrecidae and Soricidae) of the Reserve Naturelle Integrale d'Andohahela, Madagascar. A floral and faunal inventory of the Reserve Naturelle Integrale d'Andringitra. Madagascar: with reference to the elevational variation. Fieldiana: zoology New Series, 94: 187-216.

Goodman, S., P. Jenkins, D. Rakotondravony. 2000. The biogeography of rodents (Rodentia: Muridae: Nesomyinae) and tenrecids (Lipotyphla: Tenrecidae) in the eastern forests of Madagascar: An assesment of altitudinal zonation along a latitudinal gradient. Memoires de la Societe de Biogeographie, 1: 127-138.

Goodman, S., D. Rakotondravony. 2000. The effects of forest fragmentation and isolation on insectivorous small mammals (Lipotyphla) on the Central High Plateau of Madagascar. Journal of Zoology, 250: 193-200.

Goodman, S., B. Rasolonandrasana. 2001. Elevational zonation of birds, insectivores, rodents and primates on the slopes of Andrigitra Massif, Madagascar. Journal of Natural History, 35: 285-305.

Jenkins, P. 2003. Microgale, Shrew Tenrecs. Pp. 1273-1278 in S Goodman, J Benstead, eds. The Natural History of Madagascar. Chicago: The University of Chicago Press.

Jenkins, P. 1992. Description of a new species of Microgale (Insectivora: Tenrecidae) from eastern Madagascar. Bulletin British Museum of Natural History Zoology, 58(1): 53-59.

Jenkins, P., S. Goodman, C. Raxworthy. 1996. The Shrew Tenrecs (Microgale) (Insectivora: Tenrecidae) of the Reserve Naturelle Integrale d'Andringitra, Madagascar. A floral and faunal inventory of the eastern slopes of the Reserve Naturelle Integrale d'Andringitra. Madagascar: with reference to the elevational variation. Fieldiana: zoology New Series, 85: 191-217.

MacPhee, R. 1987. The Shrew Tenrecs of Madagascar: Systemic Revision and Holocene Distribution of Microgale (Tenrecidae, Insectivora). American Museum Novitates, 2889: 1-45.

Racey, P., P. Stephenson. 1996. Reproductive and energetic differentiation of the Tenrecidae of Madagascar. Biogeographie de Madagascar, 1: 307-319.

Raherisehena, M., P. Jenkins. 2008. "The IUCN Red List of Threatened Species" (On-line). Microgale cowani. Accessed November 10, 2008 at http://www.iucnredlist.org/details/40586.

Stephenson, P. 1995. Taxonomy of shrew-tenrecs (Microgale spp.) from eastern and central Madagascar. Journal of Zoology, 235: 339-350.

Stephenson, P., P. Racey. 1993. Reproductive energetics of the Tenrecidae (Mammalia: Insectivora). II. The Shrew-Tenrecs Microgale spp . Physiological Zoology, 66(5): 664-685.