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Caenolestes condorensisAndean caenolestid

By Leila Siciliano Martina

Geographic Range

Andean shrew opossums (Caenolestes condorensis) are a newly discovered species. They are currently only known to occur in the eastern slopes of the Ecuadorian Andes, within the Cordillera del Condor region. However, it is likely that this species is also found within the same environment in Peru, although it has not yet been discovered there. (Albuja and Patterson, 1996; Lunde and Pacheco, 2003; Schulenberg, et al., 1997)

Habitat

Andean shrew opossums have only been found within the Cordillera del Condor region of the Ecuadorian Andes Mountains. Compared to other regions within the Andes, Cordillera del Condor has an extremely wet environment. This area is unique in that it almost never experiences drought and has almost constant precipitation in the form of both rain and cloud condensation. In a day, this region may experience up to a couple of hours of sunlight. Andean shrew opossums have a similar habitat preference to their close relatives, gray-bellied shrew opossums (Caenolestes caniventer); both species are found in montane or sub-tropical forests. Unlike another close relative, silky shrew opossums (Caenolestes fuliginosus), both species are found in relatively lower elevations. Andean shrew opossums are likely found near vegetation less than 1.5 meters in height. (Albuja and Patterson, 1996; Patterson and Solari, 2008a; Schulenberg, et al., 1997)

Physical Description

Andean shrew opossums are marsupials; they are somewhat shrew-like in appearance, with elongated faces. Andean shrew opossums are the largest members of the genus Caenolestes. They have brownish-gray fur covering most of their body; their underside is a more solid brown in comparison. Their fur is about 10 mm in length and they have a pink nose and white whiskers. Andean shrew opossums have an average total body length of 256 mm, including a tail length of 127 mm and weigh about 48 grams. However, all of these estimates are based on the only two individuals of this species that have been captured and described. Otherwise, Andean shrew opossums are very similar in appearance to their relative, gray-bellied shrew opossums (Caenolestes caniventer). Both species are relatively robust and have similar coarse fur; however, they can be distinguished by the relatively larger body size and upper canines of Andean shrew opossums. (Albuja and Patterson, 1996; Lunde and Pacheco, 2003; Schulenberg, et al., 1997)

In general, members of family Caenolestidae can be distinguished from other marsupial groups by their unique dentition. They have a reduced number of insicors 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, which 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. All Caenolestids show sexual dimorphism, with adult males larger than adult females. (Albuja and Patterson, 1996; Lee and Cockburn, 1985; O'Connell, 2006; Osgood and Herrick, 1921; Tirira, 2007)

Common shrew opossums (Caenolestes obscurus), a close relative of Andean 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)

  • Sexual Dimorphism
  • male larger
  • Average mass
    48 g
    1.69 oz
  • Average length
    260 (including the tail) mm
    in

Reproduction

There is currently little information available regarding the mating system of Andean shrew opossums.

Female Andean 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. (O'Connell, 2006; Osgood and Herrick, 1921; Tirira, 2007; Tyndale-Biscoe and Renfree, 1987)

  • 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 Andean 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, 2008a; Timm and Patterson, 2008; Tirira, 2007)

Home Range

There is currently no information available about the individual home range of Andean shrew opossums.

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)

Food Habits

Members of genus Caenolestes are opportunistic feeders. Their stomach contents indicate that they are primarily insectivores. 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, 2008a; Schulenberg, et al., 1997; Timm and Patterson, 2008; Tirira, 2007)

  • Animal Foods
  • mammals
  • insects
  • terrestrial non-insect arthropods
  • terrestrial worms
  • Plant Foods
  • leaves
  • fruit

Predation

There is currently little information regarding the predation of Andean 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

Andean 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, 2008a; Tirira, 2007; VanZolini and Guimaraes, 1955)

Commensal/Parasitic Species

Economic Importance for Humans: Positive

Due to their human-inaccessible habitat, 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, 2008a)

Economic Importance for Humans: Negative

There are no known negative effects of Andean shrew opossums on human populations.

Conservation Status

Andean shrew opossums are currently listed as vulnerable on the IUCN Red List of Threatened Species. However, the reason for this listing is due to their limited range. Currently, this species has only been found in the Cordillera del Condor region of the Ecuadorian Andes. It is likely that Andean shrew opossums may also extend into the Peruvian region as well. (Albuja and Patterson, 1996; Patterson and Solari, 2008b)

Contributors

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

Glossary

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

acoustic

uses sound to communicate

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

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.

insectivore

An animal that eats mainly insects or spiders.

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

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

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.

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 marsupialCaenolestes. Chicago: The University of Chicago.

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

Patterson, B., S. Solari. 2008. "Caenolestes condorensis" (On-line). IUCN Red List of Threatened Species. Accessed April 20, 2013 at www.iucnredlist.org.

Schulenberg, T., K. Awbrey, G. Fabregas. 1997. The Cordillera del Condor Region of Ecuador and Peru: A Biological Assessment. Washington DC: Conservation International.

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

Tirira, D. 2007. Mamiferos del Ecuador: Guia de campo. Ecuador: 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 Barlett Publishing.

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