Animal Diversity Web

Ge­o­graphic Range

Chilean shrew opos­sums (Rhyn­c­holestes rapha­nu­rus) have only been found in a small ge­o­graphic range that cov­ers south­ern Chile, Chiloe Is­land and a small part of south­ern Ar­gentina (ap­prox­i­mately 40 de­grees south lat­i­tude and 70 de­grees west lon­gi­tude). These an­i­mals have been cap­tured at el­e­va­tions from sea level to 1,135 m. Only two spec­i­mens have been cap­tured in Ar­gentina. This species was once thought to be rare; how­ever, it is pos­si­ble that they are abun­dant in lim­ited habi­tat types. (Meserve, et al., 1982; Pat­ter­son and Gal­lardo, 1987)

• Biogeographic Regions
• neotropical
  • native

Habi­tat

Chilean shrew opos­sums re­side in tem­per­ate for­est habi­tats. Fa­vor­able mi­cro­cli­mates in­clude wet areas of south­ern beech (Nothofa­gus species) forests with plenty of coarse, woody de­bris and a thick un­der­story of shrub cover. These mar­su­pi­als are more fre­quently caught at el­e­va­tions lower than 600 me­ters. (Kelt and Mar­tinez, 1989)

• Habitat Regions
• temperate
• terrestrial

• Terrestrial Biomes
• forest
• rainforest

• Range elevation

  0 to 1135 m

  0.00 to 3723.75 ft

Phys­i­cal De­scrip­tion

Chilean shrew opos­sums are small mam­mals. Their body size can range from 10 to 13 cm. Their ven­tral and dor­sal por­tions are dark brown or gray. Their tail is shorter than their head to body length and is solid in color, with short, sparse hairs. Their body shape is shrew-like in ap­pear­ance and their ears are small and rounded. Den­tal pat­terns are used to de­ter­mine gen­der in this species, males have con­i­cal, sin­gle rooted upper ca­nines and fe­males have dou­ble-rooted ca­nines, re­sem­bling pre­mo­lars. (Pat­ter­son and Gal­lardo, 1987; Red­ford and Eisen­berg, 1992)

• Other Physical Features
• endothermic
• homoiothermic
• bilateral symmetry

• Sexual Dimorphism
• sexes alike

• Range length

  10 to 13 cm

  3.94 to 5.12 in

Re­pro­duc­tion

Lit­tle is known about caenolestid mat­ing sys­tems. The seem­ingly soli­tary be­hav­ior of Chilean shrew opos­sums, as well as the ran­dom dis­tri­b­u­tion of re­sources in their en­vi­ron­ment sug­gests a polyg­y­nan­drous (promis­cu­ous) mat­ing sys­tem. An­other hy­poth­e­sis sug­gests that these an­i­mals live in fam­ily groups and have a monog­a­mous mat­ing sys­tem. How­ever, nei­ther hy­poth­e­sis has been tested. (Kelt and Mar­tinez, 1989)

Few stud­ies have been con­ducted on the re­pro­duc­tive cycle of Chilean shrew opos­sums. Fe­males do not have a pouch and pos­sess five to seven teats. Pat­terns of teat de­vel­op­ment sug­gest lit­ters of 5 to 7 or greater. There is ev­i­dence that fe­males are ca­pa­ble of re­pro­duc­ing any time of the year, as lac­tat­ing fe­males have been cap­tured in Feb­ru­ary, March, May, Oc­to­ber, No­vem­ber and De­cem­ber. Males are thought to be re­pro­duc­tively ac­tive all year as well. They pos­sess a cleft penis and paired sperm. (Nowak, 1999; Pat­ter­son and Gal­lardo, 1987)

• Key Reproductive Features
• iteroparous
• year-round breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual
• viviparous

• Breeding interval

  Breeding intervals are unknown in Chilean shrew opossums.

• Breeding season

  Chilean shrew opossums may breed throughout the year.

• Range number of offspring

  5 to 7

Lit­tle is known about parental care of Chilean shrew opos­sums. Re­searchers have never cap­tured a fe­male with young; this may sug­gest that these an­i­mals use a nest to raise their young. In close suc­ces­sion, an adult male, an adult fe­male and two ju­ve­niles were cap­tured in one trap, lead­ing to the hy­poth­e­sis that Chilean shrew opos­sums live in fam­ily groups. If this is ac­cu­rate, both male and fe­male par­ents may par­tic­i­pate in the care of their young. How­ever, this hy­poth­e­sis has not yet been tested. (Pat­ter­son and Gal­lardo, 1987)

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

Lifes­pan/Longevity

No data has been gath­ered on the life span of Chilean shrew opos­sums. Few trapped in­di­vid­u­als have been re­cap­tured, mak­ing it dif­fi­cult to judge their life span. Be­cause of their small body size, it is likely that they do not live more than a few years. (Meserve, et al., 1982)

Be­hav­ior

Chilean shrew opos­sums are usu­ally caught at night, in­di­cat­ing that they are noc­tur­nal. They are often caught near bur­rows and under logs and ap­pear to be semi-fos­so­r­ial, for­ag­ing under leaf lit­ter for in­sects. Lack of re­cap­ture may in­di­cate trap shy­ness, high post-cap­ture mor­tal­ity or a large home range. (Kelt and Mar­tinez, 1989)

• Key Behaviors
• terricolous
• nocturnal
• motile
• sedentary

Home Range

Due to lack of re­cap­ture data or radio track­ing, home range size is not known for Chilean shrew opos­sums.

Com­mu­ni­ca­tion and Per­cep­tion

Lit­tle is known about the com­mu­ni­ca­tion of Chilean shrew opos­sums or how they per­ceive their en­vi­ron­ment. They likely have poor eye­sight due to their noc­tur­nal ac­tiv­ity and small eyes. Vib­ris­sae are used to sense in­sects and ob­jects in the en­vi­ron­ment. Ex­am­i­na­tion of their brains shows large ol­fac­tory bulbs, in­di­cat­ing an acute sense of smell. (Pat­ter­son and Gal­lardo, 1987)

• Communication Channels
• tactile
• chemical

• Perception Channels
• visual
• tactile
• acoustic
• chemical

Food Habits

Chilean shrew opos­sums are semi-fos­so­r­ial, for­ag­ing in the lit­ter layer for soil in­ver­te­brates (54% of diet) and earth­worms (7%). An­other prin­ci­ple com­po­nent of their diet is plant ma­te­r­ial and fungi (39%). When cap­tur­ing these an­i­mals, suc­cess­ful traps are com­monly baited with rolled oats. (Meserve, et al., 1988)

• Primary Diet
• carnivore
  • insectivore
• mycophage

• Animal Foods
• insects
• terrestrial non-insect arthropods
• mollusks
• terrestrial worms

• Plant Foods
• seeds, grains, and nuts

• Other Foods
• fungus

Pre­da­tion

Lit­tle data has been gath­ered on pre­da­tion of Chilean shrew opos­sums. Like most small mam­mals, they are likely a food base for noc­tur­nal car­ni­vores. Pos­si­ble ver­te­brate preda­tors in­clude vari­able hawks, white-tailed kites, Amer­i­can kestrels, black-chested buz­zard ea­gles, Har­ris's hawks, bur­row­ing owls, great horned owls, barn owls, culpeos, long-tailed snakes and Peru slen­der snakes. Chilean shrew opos­sums are small, cryp­tic, noc­tur­nal an­i­mals and likely avoid most pre­da­tion by being dif­fi­cult to find. (Jak­sic, et al., 1980; Nowak, 1999)

• Anti-predator Adaptations
• cryptic

Ecosys­tem Roles

Other than their con­sump­tion of in­sects, earth­worms, plant ma­te­r­ial and fungi, lit­tle is known about the ecosys­tem roles of Chilean shrew opos­sums. (Meserve, et al., 1988)

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

Due to few stud­ies, eco­nomic im­por­tance of Chilean shrew opos­sums is not known.

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

Due to few stud­ies, eco­nomic im­por­tance of Chilean shrew opos­sums is not known.

Con­ser­va­tion Sta­tus

As of 2012, Chilean shrew opos­sums were listed as a near threat­ened species by the IUCN (In­ter­na­tional Union for Con­ser­va­tion of Na­ture and Nat­ural Re­sources). These an­i­mals are vul­ner­a­ble due to habi­tat loss and degra­da­tion. (Diaz and Teta, 2008)

• IUCN Red List

  Near Threatened
  More information

• IUCN Red List

  Near Threatened
  More information

• US Federal List

  No special status

• CITES

  No special status

• State of Michigan List

  No special status

Con­trib­u­tors

Tanya Dewey (ed­i­tor), Uni­ver­sity of Michi­gan-Ann Arbor, Leila Si­cil­iano Mar­tina (ed­i­tor), An­i­mal Di­ver­sity Web Staff.

An­drew Moore (au­thor), Uni­ver­sity of Wis­con­sin-Stevens Point, Chris Yahnke (ed­i­tor, in­struc­tor), Uni­ver­sity of Wis­con­sin-Stevens Point.

Ref­er­ences

Diaz, M., P. Teta. 2008. "Rhyn­c­holestes rapha­nu­rus" (On-line). IUCN Red List of Threat­ened Species. Ac­cessed June 04, 2013 at www.​iucnredlist.​org.

Jak­sic, F., H. Greene, J. Yanez. 1980. The guild struc­ture of a com­mu­nity of preda­tory ver­te­brates in cen­tral Chile. Oe­colo­gia, 49: 21-28.

Kelt, D., D. Mar­tinez. 1989. Notes on dis­tri­b­u­tion and ecol­ogy of two mar­su­pi­als en­demic to the Val­vid­ian forests of south­ern South Amer­ica. Jour­nal of Mam­mal­ogy, 70: 220-224.

Meserve, P., B. Lang, B. Pat­ter­son. 1988. Trophic re­la­tions of small mam­mals in a Chilean Tem­per­ate For­est. Jour­nal of Mam­mal­ogy, 69: 721-730.

Meserve, P., R. Murua, O. Lopetegui, J. Rau. 1982. Ob­ser­va­tions on the Small Mam­mal Fauna of a Pri­mary Tem­per­ate Rain For­est in South­ern Chile. Jour­nal of Mam­mal­ogy, 63: 315-317.

Nowak, R. 1999. Mam­mals of the World. Bal­ti­more, Mary­land: John Hop­kins Uni­ver­sity Press.

Pat­ter­son, B., M. Gal­lardo. 1987. Mam­malian Species- Rhyn­c­holestes rapha­nu­rus. Amer­i­can So­ci­ety of Mam­mal­o­gists, 286: 1-5.

Red­ford, K., J. Eisen­berg. 1992. Mam­mals of the Neotrop­ics- The South­ern Cone. Chicago, Illi­nois: Uni­ver­sity of Chicago Press.