Animal Diversity Web

Ge­o­graphic Range

Gray-bel­lied shrew opos­sums (Caenolestes caniven­ter) are found in cen­tral Ecuador and north­west­ern Peru, pri­mar­ily on the Pa­cific slopes of the Andes Moun­tains. In­di­vid­u­als have been trapped in Ecuador in the fol­low­ing lo­ca­tions: El Oro Province, near Mount Cayambe and Mol­leturo. (Al­buja and Pat­ter­son, 1996; Bar­nett, 1991; Pat­ter­son and So­lari, 2008)

• Biogeographic Regions
• neotropical
  • native

Habi­tat

Gray-bel­lied shrew opos­sums re­side in sub­trop­i­cal and mon­tane forests of the Andes Slopes at el­e­va­tions above 1,500 me­ters. These an­i­mals pre­fer cool wet areas and cre­ate chan­nels under root sys­tems along streams in wet grass­lands. (Al­buja and Pat­ter­son, 1996; Bar­nett, 1991; Pat­ter­son and So­lari, 2008; Tate, 1931; Timm and Pat­ter­son, 2008)

• Habitat Regions
• tropical
• terrestrial

• Terrestrial Biomes
• forest
• mountains

• Range elevation

  1,500 (low) m

  (low) ft

Phys­i­cal De­scrip­tion

Gray-bel­lied shrew opos­sums are mar­su­pi­als, they are some­what shrew-like in ap­pear­ance, with elon­gated faces. They can be dis­tin­guished from their close rel­a­tive, silky shrew opos­sums (Caenolestes fulig­i­nosus), by the coarse thick­ness of their brown­ish-black fur. Their fur is rel­a­tively long, about 10 mm in length and is oc­ca­sion­ally tipped in white. Their un­der-fur has a gray­ish-white hue and they com­monly have dark spots on their chest. Gray-bel­lied shrew opos­sums have an av­er­age total body length of 256 mm, in­clud­ing a tail length of 127 mm and weigh about 40 grams. (Lunde and Pacheco, 2003; Os­good and Her­rick, 1921; Tirira, 2007)

In gen­eral, mem­bers of fam­ily Caenolesti­dae can be dis­tin­guished from other mar­su­pial groups by their unique den­ti­tion. They have a re­duced num­ber of in­cisors and their lower mid­dle in­cisors are large and have a for­ward slope. The den­tal for­mula for genus Caenolestes is: I 4/3, C 1/1, P 3/3, M 4/4, 46 teeth total. Their tail is long, about as long as their body, and ap­pears rat-like and hair­less, al­though it is cov­ered in white fur. While their tail is not pre­hen­sile, it is used for sup­port while they climb. Shrew opos­sums have short ro­bust limbs, each con­tain­ing 5 dig­its; their mid­dle 3 dig­its are shorter than the out­side 2. Their humeri are ex­tremely heavy; in com­par­i­son, their fe­murs are rel­a­tively slen­der. Mem­bers of fam­ily Caenolesti­dae have un­usual lip flaps, they may func­tion as a method of pre­vent­ing de­bris from in­ter­fer­ing with their whiskers or they may help pre­vent in­ges­tion of un­wanted de­bris. Sim­i­lar to other mar­su­pi­als, Caenolestid fe­males have 2 uteri and 2 vagi­nas. Mem­bers of genus Caenolestes lack a pouch but do have 4 mam­mae, 2 on ei­ther side of their ab­domen. These an­i­mals show sex­ual di­mor­phism, with adult males larger than adult fe­males. (Lee and Cock­burn, 1985; O'Con­nell, 2006; Os­good and Her­rick, 1921; Tirira, 2007)

Com­mon shrew opos­sums (Caenolestes ob­scu­rus), a close rel­a­tive of gray-bel­lied shrew opos­sums, show ev­i­dence of a low meta­bolic rate, based on their body tem­per­a­ture (35.4° C), their body weight (about 40 g), their cool habi­tat and their thick fur coat. This species shows no ev­i­dence of en­ter­ing tor­por. (McNab, 1978)

• Other Physical Features
• endothermic
• bilateral symmetry

• Sexual Dimorphism
• male larger

• Average mass

  40 g

  1.41 oz

• Average length

  256 (including the tail) mm

  in

Re­pro­duc­tion

There is cur­rently lit­tle in­for­ma­tion avail­able re­gard­ing the mat­ing sys­tem of gray-bel­lied shrew opos­sums.

Fe­male gray-bel­lied shrew opos­sums lack a mar­supium; how­ever, im­ma­ture in­di­vid­u­als may have an un­de­vel­oped fold of skin that they lose be­fore reach­ing ma­tu­rity. Fe­males have 4 mam­mae avail­able for their young to nurse. Ev­i­dence sug­gests that Caenolestid fe­males have the same num­ber of ova as mam­mae, un­like fam­ily Didel­phi­dae. In sup­port of that no­tion, a fe­male was found preg­nant with 3 em­bryos, 2 in the right uterus and 1 in the left. These an­i­mals likely have one an­nual breed­ing sea­son from Feb­ru­ary to Au­gust. Like­wise, there was a con­firmed re­port of a preg­nant fe­male trapped in the month of Sep­tem­ber. (O'Con­nell, 2006; Os­good and Her­rick, 1921; Tirira, 2007; Tyn­dale-Bis­coe and Ren­free, 1987)

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

• Breeding interval

  Members of family Caenolestidae likely breed once per year.

• Breeding season

  The breeding season of family Caenolestidae is likely between February and August.

No in­for­ma­tion is cur­rently avail­able re­gard­ing this species.

Lifes­pan/Longevity

There is cur­rently no in­for­ma­tion on the longevity of gray-bel­lied shrew opos­sums.

Be­hav­ior

Mem­bers of genus Caenolestes are soli­tary; they are pri­mar­ily ac­tive dur­ing the early evening and at night. They are ter­res­trial, but they are also adept climbers. Dur­ing the day, these an­i­mals stay in tun­nels under tree roots. When they are ac­tive, they travel through paths in dense veg­e­ta­tion. (O'Con­nell, 2006; Pat­ter­son and So­lari, 2008; Timm and Pat­ter­son, 2008; Tirira, 2007)

• Key Behaviors
• terricolous
• nocturnal
• crepuscular
• motile
• solitary

Home Range

Lit­tle is known about the home range size of this species.

Com­mu­ni­ca­tion and Per­cep­tion

Mem­bers of fam­ily Caenolesti­dae have very small eyes and poor eye­sight. Their un­usual lip flaps have the hy­poth­e­sized func­tion of clear­ing de­bris from their sen­si­tive vib­ris­sae, but they may merely func­tion as a method of pre­vent­ing the in­ges­tion of un­wanted de­bris. Their some­what prim­i­tive brains have en­larged ol­fac­tory bulbs, which could in­di­cate an en­hanced sense of smell. When they are star­tled they at­tempt to hide and they hiss when cor­nered. Caenolestids are not noted for fre­quent pro­duc­tion of sound, how­ever, cap­tive in­di­vid­u­als may make sev­eral sounds in­clud­ing whis­tles, bird-like screams, rat-like squeaks and draw­ing air through their in­cisors. (Hume, 1982; Kirsch and Waller, 1979; O'Con­nell, 2006; Vaughan, et al., 2011)

• Communication Channels
• tactile
• acoustic

• Perception Channels
• tactile
• acoustic
• chemical

Food Habits

Mem­bers of genus Caenolestes are op­por­tunis­tic feed­ers. Their stom­ach con­tents in­di­cate that they are pri­mar­ily in­sec­tiv­o­rous. In­gested in­ver­te­brates in­clude bee­tles, crick­ets, but­ter­fly lar­vae, cen­tipedes, grasshop­pers, spi­ders, and earth­worms. A smaller pro­por­tion of their diet is com­posed of veg­e­ta­tion, fruit and small ver­te­brates in­clud­ing ju­ve­nile mice. They for­age for food in moss and leaf lit­ter. When they find a food item, they ma­nip­u­late and con­sume it with their forepaws, from a semi-seated po­si­tion. As Caenolestids shear their food with their in­cisors, they pro­duce a click­ing sound. (Barkley and Whitaker, 1984; Pat­ter­son and So­lari, 2008; Timm and Pat­ter­son, 2008; Tirira, 2007)

• Primary Diet
• carnivore
  • insectivore

• Animal Foods
• mammals
• carrion
• terrestrial worms

• Plant Foods
• leaves
• fruit

Pre­da­tion

There is cur­rently lit­tle in­for­ma­tion re­gard­ing the pre­da­tion of gray-bel­lied shrew opos­sums. How­ever, there are sev­eral car­ni­vores known to in­habit a sim­i­lar range and prey upon small mam­mals, such preda­tors in­clude An­dean Moun­tain cats (Leop­ar­dus ja­co­bita), pam­pas cats (Leop­ar­dus colo­colo), culpeo foxes (Lycalopex cul­paeus) and cougars (puma con­color), among oth­ers. (Lucherini, et al., 2009)

Ecosys­tem Roles

Gray-bel­lied shrew opos­sums have an in­sec­tiv­o­rous diet. Like­wise, Caenolestids are often plagued by lice of the genus Cum­mingsia. In­ter­est­ingly, Aus­tralian mar­su­pi­als are also af­fected by sim­i­lar lice, re­lated to the fam­ily level. Caenolestids may also be­come in­fested with South Amer­i­can hard ticks (Ixodes jone­sae). (Barkley and Whitaker, 1984; Lee and Cock­burn, 1985; Pat­ter­son and So­lari, 2008; Tirira, 2007; Van­Zolini and Guimaraes, 1955)

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

Due to the hu­man-in­ac­ces­si­ble habi­tat of gray-bel­lied shrew opos­sums, there has been very lit­tle study of these an­i­mals. Like­wise, there has been very lit­tle in­ter­ac­tion be­tween human and shrew opos­sum pop­u­la­tions. They may, how­ever, serve as a con­trol of in­sect pop­u­la­tions. (Kirsch and Waller, 1979; Pat­ter­son and So­lari, 2008)

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

There are no known neg­a­tive im­pacts of gray-bel­lied shrew opos­sums on human pop­u­la­tions.

Con­ser­va­tion Sta­tus

Gray-bel­lied shrew opos­sums are cur­rently listed as a near threat­ened species on the IUCN Red List, with a de­clin­ing pop­u­la­tion. This species is par­tic­u­larly vul­ner­a­ble to habi­tat loss due to tim­ber sales and the con­ver­sion of land to agri­cul­ture. This species may not be rare within its habi­tat; how­ever, it is dif­fi­cult to as­cer­tain be­cause its range is largely in­ac­ces­si­ble to hu­mans. (Kirsch and Waller, 1979; Pat­ter­son and So­lari, 2008)

• IUCN Red List

  Lower Risk - Near Threatened

• US Federal List

  No special status

• CITES

  No special status

• State of Michigan List

  No special status

Con­trib­u­tors

Leila Si­cil­iano Mar­tina (au­thor), An­i­mal Di­ver­sity Web Staff.

Ref­er­ences

Al­buja, L., B. Pat­ter­son. 1996. A new species of north­ern shrew-opos­sum (Pauci­tu­ber­cu­lata: Caenolesti­dae) from the Cordillera del Con­dor, Ecuador. Jour­nal of Mam­mal­ogy, 77:1: 41-53.

Barkley, L., J. Whitaker. 1984. Con­fir­ma­tion of Caenolestes in Peru with in­for­ma­tion on diet. Jour­nal of Mam­mal­ogy, 65:2: 328-330.

Bar­nett, A. 1991. Records of the grey-bel­lied shrew opos­sum, Caenolestes caniven­ter and Tate's shrew opos­sum, Caenolestes tatei (Caenolesti­dae, Mar­su­pi­alia), from Ecuado­rian mon­tane forests. Mam­malia, 55:3: 443-445.

Hume, I. 1982. Di­ges­tive phys­i­ol­ogy and nu­tri­tion of mar­su­pi­als. Cam­bridge: Cam­bridge Uni­ver­sity Press.

Kirsch, J., P. Waller. 1979. Notes on the trap­ping and be­hav­ior of the Caenolesti­dae (Mar­su­pi­alia). Jour­nal of Mam­mal­ogy, 60:2: 390-395.

Lee, A., A. Cock­burn. 1985. Evo­lu­tion­ary ecol­ogy of mar­su­pi­als. Cam­bridge: Cam­bridge Uni­ver­sity Press.

Lucherini, M., J. Rep­pucci, R. Walker, M. Vil­lalba, A. Wurst­ten, G. Gal­lardo, A. Iri­arte, R. Vil­lalo­bos, P. Per­ovic. 2009. Ac­tiv­ity pat­tern seg­re­ga­tion of car­ni­vores in the high Andes. Jour­nal of Mam­mal­ogy, 90:6: 1404-1409.

Lunde, D., V. Pacheco. 2003. Shrew Opos­sums (Pauci­tu­ber­cu­lata:Caenolestes) from the Huan­camba re­gion of east An­dean Peru. Mam­mal Study, 28: 145-148.

McNab, B. 1978. The com­par­a­tive en­er­get­ics of Neotrop­i­cal mar­su­pi­als. Jour­nal of Com­par­a­tive Phys­i­ol­ogy, 125: 115-128.

O'Con­nell, M. 2006. Shrew opos­sums of the high Andes. Pp. 812 in D Mac­Don­ald, S Nor­ris, eds. The En­cy­clo­pe­dia of Mam­mals, Vol. 1, 1 Edi­tion. Lon­don: The Brown Ref­er­ence Group.

Os­good, W., C. Her­rick. 1921. A mono­graphic study of the Amer­i­can mar­su­pial, Caenolestes. Chicago: The Uni­ver­sity of Chicago.

Pat­ter­son, B., S. So­lari. 2008. "Caenolestes caniven­ter" (On-line). The IUCN Red List of Threat­ened Species. Ac­cessed May 17, 2013 at http://​www.​iucnredlist.​org/​.

Tate, G. 1931. Ran­dom ob­ser­va­tions on habits of South Amer­i­can mam­mals. Jour­nal of Mam­mal­ogy, 12:3: 248-256.

Timm, R., B. Pat­ter­son. 2008. Genus Caenolestes. Pp. 120-124 in A Gard­ner, ed. Mam­mals of South Amer­ica: Vol­ume 1- Mar­su­pi­als, Xe­narthrans, Shrews, and Bats, Vol. 1. Chicago: Uni­ver­sity of Chicago Press.

Tirira, D. 2007. Mam­if­eros del Ecuador: Guia de campo. Ecuado: Edi­ciones Mur­cielago Blanco.

Tyn­dale-Bis­coe, H., M. Ren­free. 1987. Re­pro­duc­tive phys­i­ol­ogy of mar­su­pi­als. Cam­bridge: Cam­bridge Uni­ver­sity Press.

Van­Zolini, P., L. Guimaraes. 1955. South Amer­i­can land mam­mals and their lice. Evo­lu­tion, 9:3: 345-347.

Vaughan, T., J. Ryan, N. Czaplewski. 2011. Mam­mal­ogy. Sud­bury, Mass­a­chu­setts: Jones and Bartlett Pub­lish­ing.