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Oryzorictes hovaHova rice tenrec(Also: molelike rice tenrec)

By Jonathan Fiely

Geographic Range

Mole tenrecs, Oryzorictes hova, are endemic to the island of Madagascar, the result of a spectacular radiation from the single colonizing ancestor of all Malagasy tenrecs. (Goodman, 2003)

Habitat

Mole tenrecs inhabit the forested regions of Madagascar, from lowland humid forests to high elevation localities near tree line. Although semifossorial in nature, O. hova is also broadly distributed throughout wet bottomlands including agricultural sites (converted rice paddies) and natural marshes. (Goodman and Rakotondravony, 2000; Goodman, et al., 1997; Goodman, 2003; Goodman and Rakotondravony, 2000; Goodman, et al., 1997; Goodman, 2003; Goodman and Rakotondravony, 2000; Goodman, et al., 1997; Goodman, 2003)

  • Range elevation
    0 to 1990 m
    0.00 to 6528.87 ft

Physical Description

Members of the genus Oryzorictes measure between 99 and 124 mm in length, and are between 28 g and 40 g. They share several of the morphological characters that typify semifossorial insectivores. Well developed forelimbs and elongated claws are accompanied by small eyes and ears. Albinism is expressed in some populations of O. hova, although more frequently a brown-tan bicoloration of the dorsal and ventral pelage is seen.

The principle morphological character that has defined both species of Oryzorictes is the relative number of toes on the forearm. As the name implies, Oryzorictes tetradactylus has only four toes. Other members of the genus have five toes. The relative length of the tail has also been used to distinguish O. hova and O. tetradactylus, the latter possessing a distinctly shorter tail. However significant overlap in observed tail lengths has been noted. (Goodman, 2003)

  • Sexual Dimorphism
  • sexes alike
  • Range mass
    28 to 40 g
    0.99 to 1.41 oz
  • Range length
    99 to 124 mm
    3.90 to 4.88 in
  • Average length
    112.8 mm
    4.44 in

Reproduction

Nothing is currently known on the mating systems of Oryzorictes in the wild. It is difficult to infer any pattern of mating because the family Tenrecidae shows considerable variation in their reproductive strategies. (Eisenberg and Muckenhirn, 1968; Gould and Eisenberg, 1966)

Data from specimens collected provide a limited view of this animal's reproductive life history. Embryo counts place a maximum of four in a litter, although they posses six sets of mammae. Nowak (1999) reports an average of 3 young per litter. Testes remain abdominal throughout the year as in other members of Tenrecidae. (Goodman, 2003; Gould and Eisenberg, 1966; Nowak, 1999)

  • Breeding interval
    The breeding interval ofthese animals is not known.
  • Breeding season
    Breeding season of these animals has not been reported.
  • Range number of offspring
    1 to 4
  • Average number of offspring
    3

As with other aspects of the biology of this genus, almost nothing is known about the parental investment of Oryzorictes. However, because they are mammals, we can infer that females provide a great deal of parental care to their offspring. Females nurse their young, and provide them with protection, grooming, and other care until they are weaned. It is not known whether there is further association between offspring and their parents after independence. The role of males in parental care is not known. (Nowak, 1999)

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

Lifespan/Longevity

Specimens of Oryzorictes have been successfully kept in captivity, but full lifespan data have never been published. Lifespan data for wild specimens have never been collected. Long-tailed tenrecs, in the genus Microgale have been reported to live between 5 and 6 years. Because they are similar in size to Oryzorictes, lifespans may be similar. (Goodman, 2003; Gould and Eisenberg, 1966; Nowak, 1999)

Behavior

Oryzorictes hova is a semifossorial species with locomotary adaptations similar to those of the true moles in the family Talpidae. Populations have never been noted in significant densities other than in anecdotal accounts by local farmers in rice paddies.

Daily torpor has been noted in many of the tenrecs, but has never been directly observed in Oryzorictes.

On the whole, little is known about semifossorial tenrecs. Trapping success of this species and the other semifossorial Oryzorictinae (Microgale gracilis, Microgale gymnohyncha) is very low, and often correlates with rains that flood their natural burrows. Trends in relative seasonal populations and estimated densities are unknown as a result, as O. hova handily avoids most current trapping techniques. (Eisenberg and Muckenhirn, 1968; Goodman and Rakotondravony, 2000; Goodman, 2003)

Nowak (1999) reports that members of the genus Oryzorictes are thought to be mainly nocturnal. Oryzorichtes hova is thought to sometimes forage above ground, using its muzzel to probe beneath ground cover. However, because these animals are active underground also, it is difficult to know for certain whether they move about at other times of day. (Nowak, 1999)

Home Range

Because of low trapping success of this species, the size of home ranges is not known. (Goodman, 2003)

Communication and Perception

Oryzorictes has relatively underdeveloped eyes and ears, presumably relying on its tactile senses to navigate underground. Both species possesses a long, ennervated rostrum for touch perception, and probably rely on their sense of smell to direct them to areas of high prey density. However, little is known about aspects of social communication or environmental perception beyond these morphological observations. (Goodman, 2003)

Food Habits

Nothing is known of the feeding habits of Oryzorictes other than data obtained through stomach content analyses. A high proportion of insects, earthworms, and some vegetable matter have been reported, but no further research has been conducted. (Goodman, 2003)

  • Animal Foods
  • insects
  • terrestrial worms
  • Plant Foods
  • roots and tubers

Predation

The semifossorial nature of this species protects it from many of the natural predators of Madagascar. However, remains have been observed in owl pellets and the intestinal tract of at least one fossorial snake. (Goodman, 2003)

  • Known Predators

Ecosystem Roles

The role of Oryzorictes in ecosystem function is poorly understood, as data on their natural history are almost nonexistent. Despite this, this genus of tenrecs represents a unique example of adaptation to fill an available niche. The lack an extensive predator base as found on other continents suggests Madagascar's semifossorial species do not play as critical a role as the moles and gophers of North America's varied ecosystems in sustaining predator populations. Beyond this, we can speculate that O. hova plays some role in controlling insect and earthworm populations, and may help to aerate the soil. Further speculation is not possible with the scant information known about the island's complex ecosystems. (Goodman, 2003; Goodman, 2003)

Economic Importance for Humans: Positive

Other than its inherent value as a representative species of Madagascar's endemic biota, this species has little economic importance.

Economic Importance for Humans: Negative

Oryzorictes hova has been known to inhabit rice paddies in considerable densities, causing damage to young plants by uprooting shoots while burrowing. (Goodman, 2003; Goodman, 2003)

  • Negative Impacts
  • crop pest

Conservation Status

The conservation status of these animals has not been evaluated.

Other Comments

An extensive review of the taxonomic history of Oryzorictes synonymized a previously recognized species, Oryzorictes hova with Oryzorictes hova after an extensive review of cranial and dental synapomorphies. (Goodman, 2003)

Contributors

Jonathan Fiely (author), University of Alaska Fairbanks, Link E. Olson (editor, instructor), University of Alaska Fairbanks, Nancy Shefferly (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.

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

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.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

fossorial

Referring to a burrowing life-style or behavior, specialized for digging or burrowing.

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).

marsh

marshes are wetland areas often dominated by grasses and reeds.

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.

nocturnal

active during the night

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

soil aeration

digs and breaks up soil so air and water can get in

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., N. Muckenhirn. 1968. The reproduction and rearing of tenrecoid insectivores in captivity. Internation Zoo Yearbook, 14: 108-110.

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

Goodman, S. 2003. Oryzorictes, Mole Tenrec or Rice Tenrec. Pp. 1278-1281 in S Goodman, J Benstead, eds. The Natural History of Madagascar. Chicago: University of Chicago Press.

Goodman, S., J. Ganzhorn, L. Olson, M. Pidgeon, V. Soarimalala. 1997. Annual variation in species diversity and relative density of rodents and insectivores in the Parc National de la Montagne D'Ambre, Madagascar. Ecotropica, 3: 109-118.

Gould, E., J. Eisenberg. 1966. Notes on the Biology of the Tenrecidae. Journal of Mammalogy, 47:4: 660-686.

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. 1235-1240 in S Goodman, J Benstead, eds. The Natural History of Madagascar. Chicago: University of Chicago Press.

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