Micropotamogale ruwenzoriiRuwenzori otter shrew

Geographic Range

Ruwenzori otter shrews, Micropotamogale ruwenzorii, are found in the Ruwenzori mountain range of eastern Africa, which lies between Lake Albert and Lake Edward and to the west of Lakes Edward and Kivu. ("Encyclopaedia Britannica", 2008a; Kingdon, 1974; Vogel, 2008)

Habitat

Ruwenzori otter shrews are terrestrial, semiaquatic mammals that inhabit small rivers and streams in various habitats. They are found in streams and rivers in rainforest areas, savanna edges, montane forests, and even cultivated areas, at elevations between 800 meters and 2200 meters. The temperatures in the streams and rivers that M. ruwenzorii inhabits range from 12°C to 21°C. ("Micropotamogale ruwenzorii", 1990; Kingdon, 1974; Rahm, 1960; Vogel, 2008)

  • Aquatic Biomes
  • rivers and streams
  • Range elevation
    800 to 2200 m
    2624.67 to 7217.85 ft

Physical Description

The common name of M. ruwenzorii, Ruwenzori otter shrew, is a misnomer. Micropotamogale ruwenzorii is neither an otter (Lutrinae) nor a shrew (Soricidae), although they may look like large shrews. Ruwenzori otter shrews have relatively large feet for animals of their size and they are broad and webbed. Micropotamogale ruwenzorii is the only species in the genus Micropotamogale to have webbed feet. The second and third toe of the hind foot are syndactylous. At the end of the notably wide rostrum is a large pad surrounded by stout whiskers. The head and body of M. ruwenzorii is 123 mm to 200 mm and is covered by dark, dense, otter-like fur. The tail is long (100 mm to 150 mm) with course hairs along the top and bottom. Weights of M. ruwenzorii range from 75 g to 135 g. Ruwenzori otter shrew display many of the adaptations to semiaquatic carnivory reviewed by Benstead and Olson (2003). These include webbed hind feet, dense soft fur with abundant guard hairs, and a rounded tail with conspicuously longer hairs located ventrally. ("Encyclopaedia Britannica", 2008b; Benstead and Olson, 2003; Kingdon, 1974; Rahm, 1960; Rahm, 1961; Stephan, et al., 1986; Vogel, 2008)

  • Range mass
    75 to 135 g
    2.64 to 4.76 oz
  • Range length
    223 to 350 mm
    8.78 to 13.78 in

Reproduction

No information regarding the mating systems of M. ruwenzorii is readily available.

As with mating systems, there is no information published regarding the general mating behavior of M. ruwenzorii. In September 1960, Rahm collected a female specimen whose two embryos had well-developed whiskers. Furthermore, two female specimens were collected in February 1984, each with a single embryo. It is possible that, due to its tropical distribution, M. ruwenzorii breeds year-round. Other than these rudimentary inferences, no other information regarding reproductive behavior in M. ruwenzorii is available. (Rahm, 1960; Stephan, et al., 1986)

  • Range number of offspring
    1 to 2

The few embryos of M. ruwenzorii that have been collected indicate that parental investment may be high. It appears that M. ruwenzorii is a K-selected mammal, which indicates later maturation, low fecundity, and high parental care of offspring. (Rahm, 1960; Stephan, et al., 1986)

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

Lifespan/Longevity

No information regarding lifespan of M. ruwenzorii is available.

Behavior

Ruwenzori otter shrews spend most of their time in and around water, mostly streams and small rivers. They are nocturnal, with hunting, resting and grooming being the primary activities. Observations have shown that they emerge from burrows in the late evening and alternately hunt and rest. Resting is accompanied by grooming and scratching. Burrows usually consist of a tunnel dug into an earthen bank with a sleeping chamber or nest built out of dried grasses and twigs at the end. The entrances to these hollows are underwater.

Ruwenzori otter shrews swim with pectoral and pelvic strokes. They swim at the surface with the head and upper back out of the water. While they have robust, strong tails, they are not used for propulsion. Deep dives are propelled by a strong unison stroke by all four legs. Swimming sessions are typically short and they frequently return to shore to groom. (Kingdon, 1974; Rahm, 1961; Vogel, 2008)

Home Range

Home range sizes are not reported.

Communication and Perception

Ruwenzori otter shrews rely heavily on tactile sensory perception. It is thought that the presence of whiskers from even an embryonic age shows the importance of vibrissae in this species. No information on communication between individuals is available. (Kingdon, 1974; Rahm, 1961)

Food Habits

Micropotamogale ruwenzorii individuals feed primarily in the water or along river banks. Presumably, the stout leathery nose pad protects the nose as they forage on the bottom, using their whiskers to find prey. They eat insect larvae and worms as well as small fish, frogs, and crabs, which they grab from behind. If prey cannot be eaten quickly underwater, it is taken to land and bitten rapidly until it is subdued. (Kingdon, 1974; Rahm, 1961; Vogel, 2008)

  • Animal Foods
  • amphibians
  • fish
  • insects
  • terrestrial non-insect arthropods
  • mollusks
  • terrestrial worms
  • aquatic or marine worms
  • aquatic crustaceans

Predation

While no information pertaining to specific predators is available, it is assumed that M. ruwenzorii is susceptible to predation by larger carnivores or aerial predators.

Ecosystem Roles

The range of M. ruwenzorii overlaps that of the giant otter shrew (Potamogale velox), yet there is no published evidence of their interactions. As noted above, M. ruwenzorii tends to prefer small rivers and streams. Potamogale velox, on the other hand, can be found in larger rivers and lakes. (Kingdon, 1974)

Economic Importance for Humans: Positive

There is no recorded or perceived positive economic importance to humans from M. ruwenzorii.

Economic Importance for Humans: Negative

There is no recorded or perceived negative economic importance to humans from M. ruwenzorii.

Conservation Status

Micropotamogale ruwenzorii is classified as Near Threatened by the ICUN. It has a limited range and it appears that M. ruwenzorii responds negatively to increasing human densities. (Vogel, 2008)

Other Comments

Micropotamogale ruwenzorii was once placed in its own monotypic genus, Mesopotamogale. (Rahm, 1960; Rahm, 1961)

Contributors

Tanya Dewey (editor), Animal Diversity Web.

James Smith (author), University of Alaska Fairbanks, Link Olson (editor, instructor), University of Alaska Fairbanks.

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.

freshwater

mainly lives in water that is not salty.

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.

natatorial

specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

piscivore

an animal that mainly eats fish

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

riparian

Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).

scrub forest

scrub forests develop in areas that experience dry seasons.

sedentary

remains in the same area

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

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.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

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

2008. "Encyclopaedia Britannica" (On-line). Otter Shrew. Accessed November 17, 2008 at http://search.eb.com/eb/article-9057673.

2008. "Encyclopaedia Britannica" (On-line). Ruwenzori Range. Accessed November 17, 2008 at http://search.eb.com/eb/article-9064527.

1990. Micropotamogale ruwenzorii. Pp. 19 in M Nicoll, G Rathbun, eds. African Insectivora and Elephant-Shrews. Switzerland: International Union for Conservation of Nature and Natural Resources.

Benstead, J., L. Olson. 2003. Limnogale mergulus. Pp. 1267-1273 in S Goodman, J Benstead, eds. Natural History of Madagascar. Chicago: University of Chicago Press.

Kingdon, J. 1974. Micropotamogale ruwenzorii. Pp. 11-13 in J Kingdon, ed. East African Mammals, Vol. 2. London: The University of Chicago Press.

Rahm, U. 1961. Beobachtungen an der ersten in Gefangenschaft gehaltenen Mesopotamogale Ruwenzorii (Mammailia-Insectivora). Rev. Suisse de Zolologie, 68: 73-90.

Rahm, U. 1960. Note sur les specimens actuellement connus de Micropotamogale (Mesopotamogale) ruwenzorii et leur repartition. Mammalia, 24: 511-515.

Stephan, H., K. Ka Mubalamata, M. Stephan. 1986. The Brain of Micropotamogale ruwenzorii (De Witte and Frechkop, 1955). Z. Saugertierkunde, 51: 193-204.

Vogel, P. 2008. "Micropotamogale ruwenzorii" (On-line). 2008 IUCN Red List of Threatened Species. Accessed November 17, 2008 at http://www.iucnredlist.org/details/13394.