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By Jessica Lench
Geographic Range
Asian musk shrews (Suncus murinus) originated from the Indian subcontinent, ranging from southern Asia and Afghanistan to the Malay archipelago and southern Japan. This species has been introduced into northern and eastern Africa and the Middle East. Asian musk shrews are associated with forest environments, but are commonly found in household communities, and are considered commensals of humans. ("IUCN Invasive Species Specialist Group and Global Invasive Species Data Base", 2004)
Biogeographic Regions:
palearctic 
(introduced , native ); oriental (native ); ethiopian (introduced ); oceanic islands (introduced ).
Habitat
This species is found in forested areas, in agricultural lands, and in areas associated with human activity. There have been many studies showing that S. murinus is found in many houses and businesses. It is primarily terrestrial. ("IUCN Invasive Species Specialist Group and Global Invasive Species Data Base", 2004; Mushtaq-Ul-Hassan-Muhammad et al., 1999)
Nesting occurs wherever possible. In the forest/agricultural habitat, these shrews gather leaves and any other nesting material available, then find a hidden area (snag) in which to build the nest. In a house or business this species nests in dark hidden areas, and uses any type of loose material that can be found for nest construction. (Mushtaq-Ul-Hassan-Muhammad et al., 1999)
These animals are found in the following types of habitat:
temperate ; tropical ; terrestrial .
Terrestrial Biomes:
forest .
Other:
urban ; suburban ; agricultural .
Physical Description
(0.81 to 5.18 oz)
(3.94 to 5.91 in)
Asian musk shrews vary widely in color, size, and weight. They are mouse-like in appearance, with a long pointed nose. The fur color varies, with some individuals light gray to those which are black. Pelage is short and has a velvety texture. ("IUCN Invasive Species Specialist Group and Global Invasive Species Data Base", 2004; Chang-Chun-Hsiang, 1999)
The weight of an adult female ranges between 23.5 g and 82.0 g. Males are much heavier, weighing in from 33.2 g to 147.3 g. Asian musk shrews are very small in size. Total body length of adults typically varies between 100 mm and 150 mm, including the tail. The males have a large, well-developed scent gland, from which is derived the strong, musky odor, for which they received their common name. ("IUCN Invasive Species Specialist Group and Global Invasive Species Data Base", 2004; Chang-Chun-Hsiang, 1999)
Some key physical features:
endothermic ; bilateral symmetry .
Sexual dimorphism: male larger.
Reproduction
These animals can breed approximately once per month.
This species breeds year round, although there are breeding peaks in spring and summer.
No information was found on the mating system of Asian musk shrews. The size dimorphism between males and females suggests that the species might be polygynous, however, both male and female are known to collect nesting material apparently prior to parturition, suggesting that mating may be monogamous. Another member of the same genus, Suncus varilla, is reportd to be monogamous. (Nowak, 1999)
Reproduction occurs all year round with peaks in the spring and summer seasons. There is no behavioral oestrus cycle, and development of follicles and ovulation are induced by mating. The sperm spends a long period in the female's reproductive tract before fertilization occurs. The gestation period is usually 30 days and litter size varies from 4 to 8. The young stay in the nest until they are about seventy-five percent grown. Weaning occurs between 15 and 20 days, although young can survive forced weaning as early as 12 days of age. Females reach sexual maturity around 35 days. ("IUCN Invasive Species Specialist Group and Global Invasive Species Data Base", 2004; Mushtaq-Ul-Hassan-M et al., 2000; Nowak, 1999)
Key reproductive features:
iteroparous ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; induced ovulation ; fertilization ; viviparous ; sperm-storing ; delayed fertilization .
Both parents gather nesting material and the young do not leave the nest until seventy-five percent grown. As mammals, the female provides the offspring with milk, and probably grooms them while they are in the nest. Little is known about male parental care, beyond the gathering of nesting material. ("IUCN Invasive Species Specialist Group and Global Invasive Species Data Base", 2004; Nowak, 1999)
Parental investment:
no parental involvement; altricial ; pre-fertilization (protecting: female); pre-hatching/birth (provisioning: female, protecting: female); pre-weaning/fledging (provisioning: female, protecting: male, female); pre-independence (provisioning: female, protecting: female).
Lifespan/Longevity
The lifespan of S. murinus in captivity ranges from 1.5 to 2.5 years. However, shrews generally live between one and two years of age in the wild. ("IUCN Invasive Species Specialist Group and Global Invasive Species Data Base", 2004; Nowak, 1999; Schmidt, 1994)
Behavior
This is a robust and highly adaptable species. Because of this, theese shrews colonize at high densities. These shrews are nocturnal and active year round. They are typically terrestrial, and are thought to be mainly solitary. ("IUCN Invasive Species Specialist Group and Global Invasive Species Data Base", 2004)
Home Range
The home range size for these animals has not been reported.
Communication and Perception
Shrews apparently are solitary and intollerant of conspecifics. Their vocal sounds include a high proportion of chirps and buzzes, sounds that seem to be associated with aggressive behavior. In China S. murinus is known as the "money shrew" because of a resemblance between its rather constant, small chattering noises, and the sound of jingling coins. (Nowak, 1999)
In addition to vocal communication, these animals are likely to use some chemical cues in communicating, especially the males, which have very pronounced scent glands. ("IUCN Invasive Species Specialist Group and Global Invasive Species Data Base", 2004; Nowak, 1999)
Other forms of communication in these animals must be inferred from the fact that they are mammals. Tactile communication probably occurs between mates, between mothers and their young, and between individuals in aggressive encounters. Because they are mammals, these shrews have some ability to see, although shrews are not known for having well-developed eyes. So, although some visual signals may exist in this species, they are probably not as important as other forms of communication. (Nowak, 1999)
Other communication keywords:
scent marks .
Food Habits
Suncus murinus is mainly insectivorous. Eighty-two percent of their diet constitutes insects and mammals. Asian musk shrews are also known to be opportunistic feeders. In most areas, they feed on plant material and also tend to eat a wide variety of invertebrates and human food items. They are nocturnal and feed mostly at night in forests, cultivated fields, and human populated areas. ("IUCN Invasive Species Specialist Group and Global Invasive Species Data Base", 2004; Prakash-Ishwar and Singh-Himmat, 1999)
Like many other shrews, this species has a high metabolic rate, and requires multiple feeding periods. ("IUCN Invasive Species Specialist Group and Global Invasive Species Data Base", 2004; Prakash-Ishwar and Singh-Himmat, 1999)
Primary Diet:
carnivore (insectivore ).
Animal Foods:
insects; terrestrial non-insect arthropods.
Plant Foods:
seeds, grains, and nuts.
Predation
- brown tree snakes (Boiga irregularis)
Suncus murinus has few predators because of its well-developed scent gland. This gland produces a strong odor of musk that inhibits many possible predators. Among notable predators are brown tree snakes. (Pickett, 1995)
Ecosystem Roles
Suncus murinus is a dominant species in the mammal population in its natural environment. It undoubtedly affect many insect populations due to its voracious feeding behavior. (Prakash-Ishwar and Singh-Himmat, 2002)
Economic Importance for Humans: Negative
Suncus murinus is an invasive species. They have a rapid reproductive rate, and they are not eaten by many potential predators because they are so smelly. These shrews are a growing ecological threat, preying upon or competing with many plant and animal species. Due to high densities in household areas, this species is labeled as a pest and can be very damaging to foods and other materials found in homes and businesses. ("IUCN Invasive Species Specialist Group and Global Invasive Species Data Base", 2004; Takata-Takashi et al., 1999; Tsuji-Keiichiro et al., 1999)
Ways that these animals might be a problem for humans:
household pest.
Economic Importance for Humans: Positive
Predation on many insects is an important role in musk shrews, and probably helps to curb the population of many pest species. These shrews are also being used as a potential medical models for humans, especially in the study of periodontal disease in humans. Other research uses of S. murinus include behavioral studies in comparative psychology and related fields. ("IUCN Invasive Species Specialist Group and Global Invasive Species Data Base", 2004; Takata-Takashi et al., 1999; Tsuji-Keiichiro et al., 1999)
Ways that people benefit from these animals:
research and education; controls pest population.
Conservation Status
IUCN Red List: [link]:
Lower Risk - Least Concern.
US Federal List: [link]:
No special status.
CITES: [link]:
No special status.
This species is listed as an invasive species and is not protected. This species is trapped and poisoned in domestic areas. Dogs may also be used to eliminate this species in these areas. ("IUCN Invasive Species Specialist Group and Global Invasive Species Data Base", 2004)
Other Comments
Asian house shrews have many other common names associated with it such as: house shrew, Indian musk shrew, kirkanjia. ("IUCN Invasive Species Specialist Group and Global Invasive Species Data Base", 2004)
Contributors
Jessica Lench (author), University of Wisconsin-Stevens Point. Chris Yahnke (editor, instructor), University of Wisconsin Stevens Point.
Nancy Shefferly (editor), Animal Diversity Web Staff.
