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Crossarchus obscuruslong-nosed cusimanse

By Stacie Holmes

Geographic Range

Crossarchus obscurus is native to West Africa. It is found in the high forest zone and the associated riparian forests of Ghana, Ivory Coast, Liberia, Sierra Leone, and possibly Guinea. (Goldman, 1987)

Habitat

This mongoose differs from the other social mongooses (Helogale, Mungos, Suricata) in that it lives in the high forests of Western Africa and not in the open areas that these other species normally occupy. Other mongooses are typically found in savannas, woodlands, open grasslands, and semi-arid bush. Crossarchus obscurus is often found near water. It eats food found near and in the water's edge, along with the food it finds in the dense ground cover vegetation of the high forests. These animals also forage in old agricultural lands that are returning to forest. (Goldmand, 1987). Crossarchus obscurus occurs at elevations between sea level and 1,000 m.

  • Range elevation
    0 to 1000 m
    0.00 to 3280.84 ft

Physical Description

Cusimanses are small mongooses. They have a slender body with short legs and a short tail (146 to 210 mm) that tapers evenly from its base to its tip. The forelimbs are plantigrade, while it is uncertain whether the hindlimbs are plantigrade or semidigitgrade. Claws on the forefeet are longer than those on the hindfeet, but both have well developed digital, interdigital, thenar, and hypothenar pads. Also, the soles of the hindfeet are naked (without fur) except for the last one-third by the heel. The head of this animal has round, short ears, and a snout that extends well beyond the lower lip. The pupils of the eyes have the shape of elongated (horizontally) ovals. Females of this species have six mammae and both sexes have a pair of anal scent glands. (Goldmand, 1987).

The fur on these animals varies in texture and in color. Body fur color tends to be a mix of browns, greys, and yellows. The guard hairs are long and bristle-like and lighter in color at their tips. The dense underfur is lighter in color than the guard hairs. The fur on the legs is a darker blackish-brown. Facial fur tends to be lighter and shorter than that of the rest of the body. (Goldmand, 1987).

The skull of C. obscurus is characterized by a long, narrow, and elongated rostrum. Also, the posterior margin of the palatine is evenly emarginated. The dental formula is i3/3, c1/1, p3/3, m2/2, with a total of 36 teeth. (Goldmand, 1987).

  • Range mass
    454 to 1000 g
    16.00 to 35.24 oz
  • Average mass
    790 g
    27.84 oz
  • Range length
    440 to 560 mm
    17.32 to 22.05 in
  • Average length
    510 mm
    20.08 in

Reproduction

Individuals of the species reach sexual maturity in nine months. Females are polyestrus, meaning they go into estrus more than one time per year. Goldman (1987) reported, "when not pregnant a captive repeatedly came into estrus on nine occasions in 13 months." The males initiate and terminate copulation. Young cusimanses are born following an eight week gestation period. Litter sizes can range from 2 to 4 individuals, but the usual size is four. It is possible for females to have 2 to 3 litters per year. At birth the young are 9 to 10 mm long (head and body length combined) and have a tail that is 3 mm long. These animals are born with closed eyes, fur on their bodies (including under fur), short rostrums, and large forelimbs. After 12 days the eyes are open and in captivity young are eating solid food within three weeks. By week five guard hairs appear.

  • Range number of offspring
    2 to 4
  • Average number of offspring
    4
  • Average number of offspring
    4
    AnAge
  • Average gestation period
    8 weeks
  • Average gestation period
    58 days
    AnAge
  • Average age at sexual or reproductive maturity (female)
    9 months
  • Average age at sexual or reproductive maturity (female)
    Sex: female
    274 days
    AnAge
  • Average age at sexual or reproductive maturity (male)
    9 months
  • Average age at sexual or reproductive maturity (male)
    Sex: male
    274 days
    AnAge

Lifespan/Longevity

In captivity, C. obscurus is known to live nine years (Goldman, 1987).

Behavior

Crossarchus obscurus is a gregarious species, highly social, and diurnal. These animals tend not to stay in one place for long and will wander in circles over their territories. As they wander, they seek refuge under logs or in hollowed out logs, in thick vegetation, or in burrows that they find. Members of this species has also been known to dig their own burrows or to dig into termite mounds for shelter (Goldman, 1987).

This mammal has displayed play behavior in both the wild and in captivity. Threat displays have also been observed. Goldman (1987) reported that pet animals that have been attacked by dogs much larger than their own size have not hesitated to get into a threat position, which includes arching the back, extending the limbs, and hairs becoming fully erect.

In captivity, comfort movements such as yawning and stretching have been observed. Grooming is rudimentary. (Goldman, 1987).

Communication and Perception

Food Habits

This mammal kills it prey with one single bite to the back of the neck, but they do not shake their prey. Cusimanses forage at night, individually or in groups (up to 20 or more) (Goldman, 1987). Their foraging techniques include scratching and digging at leaf litter and soil with their claws and turning over woody debris and stones. Snouts are also used to push around material while foraging. They do this to find insects, larvae, small reptiles, crabs, tender fruits, and berries, all of which are the main components of their diets (Nowak, 1999). In their search for prey, C. obscurus has been observed climbing slanted trees and foraging in the water to find freshwater crabs (Goldman, 1987).

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

Predation

Crossarchus obscurus is often preyed upon by larger carnivores and birds of prey (Goldman, 1987).

Ecosystem Roles

Ecoparasites such as ticks, lice, and fleas are often found living on this species (Goldman, 1987).

Economic Importance for Humans: Positive

Since cusimanses are easily trained they are often kept as pets (Goldman, 1987).

Conservation Status

Other Comments

Most of the information available on this species is a result of studies that have been done on animals in captivity. Field research is lacking (Goldman, 1987). Crossarchus obscurus is a monotypic species meaning that no subspecies occur. Speciation in the genus Crossarchus occurred in the Pleistocene in association with climatic and vegetational changes that occurred during the Quaternary Period. As cycles of moist and arid conditions occurred during this time, there were repeated reductions of the high forest zone during the arid phases. This resulted in the formation of refugia or relect areas of the high forest. During the arid phases these refuges would maintain populations of the ancestor species. Allopatric speciation in each of these refugium resulted in the four species of this genus that occur today.(Goldman, 1984).

Contributors

Stacie Holmes (author), University of Michigan-Ann Arbor, Bret Weinstein (editor), University of Michigan-Ann Arbor.

Glossary

Ethiopian

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

World Map

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.

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.

fertilization

union of egg and spermatozoan

forest

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

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.

omnivore

an animal that mainly eats all kinds of things, including plants and animals

pet trade

the business of buying and selling animals for people to keep in their homes as pets.

sexual

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

social

associates with others of its species; forms social groups.

tactile

uses touch to communicate

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

References

Goldman, C. 1987. *Crossarchus obscurus*. Mammalian Species, 290: 1-5.

Goldman, C. 1984. Systematic revision of the African mongoose genus *Crossarchus* (Mammalia: Viverridae). Canadian Journal of Zoology, 62: 1618-1630.

Nowak, R. 1999. Walker's Mammals of the World. Baltimore: John Hopkins University Press.

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