Mustela lutreolinaIndonesian mountain weasel

Geographic Range

Indonesian mountain weasels are only found on the islands of Java and Sumatra in Indonesia. Indonesian mountain weasels are island endemic and native to the Oriental biogeographic ragion. More surveys need to be conducted in these areas to determine their exact distribution and home ranges. (Duckworth, et al., 2008)


Indonesian mountain weasels, as their names suggests, live in the tropical rainforest mountainous regions of Indonesia. However, very little is known about their preferred habitat conditions besides their preference for higher elevations. It is believed that their elevation ranges from 1,000 m to 2,200 m, but little is known of how they function at extreme elevations or if they can live outside of their range. According to the IUCN there are only 15 known specimen of the Indonesian mountain weasel, and of those only 12 have a locality. More surveys and research is needed to determine habitat range and preference. (Duckworth, et al., 2008)

  • Range elevation
    1,000 to 2,200 m
    to ft

Physical Description

The Indonesian mountain weasel as a weasel has very specific traits that all in their genus share. Weasels have long, slender bodies with short legs. This body design allows them to enter any place in which they can stick their heads. A long slender body has costs; while their metabolic rate tends to be similar to other mammals of the same size, they tend to lose heat much faster due to their shape (Brown and Lasiewski, 1972). The Indonesian mountain weasel tends to be between 279 m and 321 m from head to the base of the tail. The tail is about 136 mm to 170 mm long (Eaton, 2009). There is very little information specifically on the Indonesian mountain weasel, however, we know that they have reddish-brown fur and a foramen on their skull by which they can be identified. This foramen is located "in the medial part of the auditory bullae, mid-way along the anterior-posterior axis, at the point where the bullae attach to the skull" (Meiri, Duckworth, and Meijarrd, 2007). (Eaton, 2009; Meiri, et al., 2007; Walker, et al., 1964)

  • Sexual Dimorphism
  • male larger
  • Range mass
    295 to 340 g
    10.40 to 11.98 oz
  • Range length
    297 to 321 mm
    11.69 to 12.64 in


As a member of the badgers, otters, and weasels family, Indonesian Mountain weasels have a polygnous mating system in which the males will fight for access to a female. It is noted that these fights can be extremely vicious. Weasels are solitary creatures and the mating season is often the only time adults will interact with one another. This type of behavior is called a solitary-territorial mating system (Bright, 2000). The specifics of Indonesian mountain weasel mating habits are unknown. (Bright, 2000; Moors, 1980)

Indonesian mountain weasels become sexually mature at about a year of age. Their breeding season is believed to be between March and May, followed by a gestation period of approximately 30 days. ndonesian mountain weasels, like other weasels, give birth to altricial young. This means that the young are born with their eyes shut and with very little fur. The pups rely solely on their mother for care. It takes about a month for pups eyes to fully open, and another month after which they will become fully weaned. ("Indonesian Mountain Weasel", 2004)

  • Breeding interval
    The frequency of Indonesian mountain weasel breeding is unknown.
  • Breeding season
    Indonesian mountain weasels mate from March to May.
  • Range number of offspring
    2 to 12
  • Average gestation period
    30 days
  • Average time to independence
    2 months
  • Average age at sexual or reproductive maturity (female)
    1 years
  • Average age at sexual or reproductive maturity (male)
    1 years

For weasels, care of young fall on the mother alone. Even though the young are altricial, they are fully weaned after 2 months and leave their mother. However, the litter tends to prefer to remain together until Autumn. ("Indonesian Mountain Weasel", 2004)


Little is known about how long Indonesian mountain weasels live, but some suggest between 7 to 10 years of age (, 2004). Nor do they known about the lifespan of Indonesian mountain weasels in captivity. However, other species of weasels live up to 20 years in the wild and do very well in captivity (Walker et al., 1964). (Walker, et al., 1964; "Indonesian Mountain Weasel", 2004)

  • Typical lifespan
    Status: wild
    7 to 10 years


Very little is known about the behavior of the Indonesian mountain weasel. Other weasels tend to be solitary and nocturnal only interacting for breeding or over territory disputes. (Walker, et al., 1964)

Home Range

Since they have a solitary-territorial mating system, a females main concern is defending a home range that will provide sufficient resources for her offspring. Whereas males want to have a home range that will contain as many females as possible. However, the exact range for them is unknown. (Johnson, et al., 2000)

Communication and Perception

As with other weasel species Indonesian mountain weasels will communicate primarily with odors and secondarily with "clicks" or other auditory noises. (Erlinge and Sandell, 1988)

Food Habits

Weasels are completely carnivorous and the Indianian mountain weasel is no different. They are especially adapted to eating rodents; their agility and speed allows them to take down prey much larger than themselves. They are also very good at removing rodents from their burrows. Some species of weasels are known to stay at one prey den until they have completely eliminated all of the inhabitants. (Walker, et al., 1964)

  • Primary Diet
  • carnivore
    • eats terrestrial vertebrates
    • eats eggs
  • Animal Foods
  • birds
  • mammals
  • amphibians


Indonesian mountain weasels have no known predators, aside from humans. It is believed that due to their fierce nature, it would not be worth a predators effort to attempt to consume them. It is believed that some weasel species are eaten by foxes. While there are no foxes in Indonesia it is possible some of the other carnivores might be a threat to Indonesian mountain weasels. (Bright, 2000)

Ecosystem Roles

Weasels are pest controlers and have been known to eradicate species from their home ranges. (Moors, 1980)

Economic Importance for Humans: Positive

Indonesian mountain weasels are known to keep rodent populations in check; a common pest for humans. (Walker, et al., 1964)

  • Positive Impacts
  • controls pest population

Economic Importance for Humans: Negative

No specific negative effects to humans are known, but weasels are known to eat poultry. This can be a big problem for farmers in the area who use poultry as a main source of income or food. (Walker, et al., 1964)

  • Negative Impacts
  • household pest

Conservation Status

Indonesian mountain weasels are endangered because they are endemic to a very small area and because they are very poorly known. They are among the rarest of the weasel family and face issues with habitat fragmentation. Habitat fragmentation has a very strong correlation with declines in weasel abundance. (Bright, 2000)


Amelia Hunt (author), University of Alaska Fairbanks, Laura Prugh (editor), University of Washington, Laura Podzikowski (editor), Special Projects.



uses sound to communicate


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.


an animal that mainly eats meat


uses smells or other chemicals to communicate


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.

female parental care

parental care is carried out by females


Referring to a burrowing life-style or behavior, specialized for digging or burrowing.

island endemic

animals that live only on an island or set of islands.


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).


having the capacity to move from one place to another.


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.


active during the night


found in the oriental region of the world. In other words, India and southeast Asia.

World Map


having more than one female as a mate at one time


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.

scent marks

communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them

seasonal breeding

breeding is confined to a particular season


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


lives alone


uses touch to communicate


Living on the ground.


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


uses sight to communicate


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

References 2004. "Indonesian Mountain Weasel" (On-line). Indonesian Fauna. Accessed October 01, 2012 at

Amstislavsky, S., Y. Ternovskaya. 2000. Reproduction in mustelids. Animal Reproduction Science, 60-61: 571-581.

Bright, P. 2000. Lessons from lean beasts: conservation biology of the mustelids. Mammal Review, 30: 217-226.

Brown, J., R. Lasiewski. 1972. Metabolism of Weasels: The Cost of Being Long and Thin. Ecology, 53: 939-943.

Duckworth, J., L. Barney, A. Abramov. 2008. "Mustela Lutreolina" (On-line). IUCN Red List. Accessed October 01, 2012 at

Eaton, J. 2009. An Observatino of Indonesian Mountain Weasel Mustela Lutreolina at Gunung Kerinci, Sumatra, Indonesia.. Small Carnivore Conservation, 40: 27-28.

Erlinge, S., M. Sandell. 1988. Coexistence of stoat, Mustela erminea, and weasel, M. nivalis: social dominance, scent communication, and reciprocal distribution. OIKOS, 53: 242-246.

Johnson, D., D. MacDonald, A. Dickman. 2000. An analysis and review of the sociobiology of Mustelidae. Mammal Review, 30: 171-196.

Meiri, S., J. Duckworth, E. Meijaard. 2007. Biogeography of Indonesian Mountain Weasel Mustela lutreolina and a newly discovered specimen. Small Carnivore Conservation, 37: 1-5.

Moors, P. 1980. Sexual dimorphism in the body size of mustelids (Carnivora): the rolse of food habitas and breeding systems. OIKOS, 34: 147-158.

Walker, E., F. Warnick, K. Lange, H. Uible, M. Davis, P. Wright. 1964. Mammals of the World Volume II. Baltimore: Johns Hopkins Press.