Taxonomic name: Suncus murinus (Linnaeus, 1766)
Synonyms: Suncus albicauda, Suncus albinus, Suncus andersoni, Suncus auriculata, Suncus beddomei, Suncus blanfordii, Suncus blythii, Suncus caerulaeus, Suncus caerulescens, Suncus caeruleus, Suncus celebensis, Suncus ceylanica, Suncus crassicaudus, Suncus duvernoyi, Suncus edwardsiana, Suncus fulvocinerea, Suncus fuscipes, Suncus geoffroyi, Suncus giganteus, Suncus griffithii, Suncus heterodon, Suncus indicus, Suncus kandianus, Suncus kroonii, Suncus Kuekenthali, Suncus leucera, Suncus luzoniensis, Suncus malabaricus, Suncus mauritiana, Suncus media, Suncus melanodon, Suncus microtis, Suncus mulleri, Suncus muschata, Suncus myosurus, Suncus nemorivagus, Suncus nitidofulva, Suncus occultidens, Suncus palawanensis, Suncus pealana, Suncus pilorides, Suncus riukiuana, Suncus rubicunda, Suncus sacer, Suncus saturatior, Suncus semmeliki, Suncus semmelincki, Suncus serpentarius, Suncus sindensis, Suncus soccatus, Suncus sonneratii, Suncus swinhoei, Suncus temminckii, Suncus tytleri, Suncus unicolor, Suncus viridescens, Suncus waldemarii
Common names: Asian house shrew (English), Asian musk shrew (English), brown musk shrew (English), Ceylon highland shrew (English-Sri Lanka), common Indian musk-shrew (English-Sri Lanka), grande pachyure (French), grey musk shrew (English-India), house shrew (English), Indian grey musk-rat (English-Sri Lanka), Indian musk shrew (English), Kandyan shrew (English-Sri Lanka), kirukanjia (Swahili), money shrew (English-China), Moschusspitzmaus (German), musaraigne musquée (French), rat musquee (Mauritian Creole), Ryukyu musk shrew (English-Japan), white-tailed shrew (English-Bangladesh)
Organism type: mammal
Suncus murinus (the Indian musk shrew) is a commensal and adaptable mammal. It is a rapid coloniser and threatens many plant and animal species through predation and competition. Through human agency it has a large and expanding range and, to date, very little work has been done on how to effectively manage the species.
A highly variable species, the Indian musk shrew (Suncus murinus) varies widely in colour, size and weight. It is small, secretive and mouse-like with a long pointed nose. The fur is short and velvety, ranging in colour from light grey-brown to black and recorded adult weights vary between 23.5g to 82.0g in females and 33.2g to 147.3g in males (Ruedi et al., 1996). The head-to-body length of S. murinus is up to 15cm, the tail length up to 8cm (Baker, 2005). A study comparing shrew populations from Guam and Madagascar showed some significant differences in appearance, body weight and length, with female shrews from Madagascar being heavier than females from Guam (Hasler et al. 1977). Chang et al. (1999a,b) found that the average weight of adult females in Taiwan was 37.4g, and the average weight of juvenile females was 23.2g, while the average weight of adult males was 58.6g, and the average weight of juvenile males was 32.9g. Musk shrews have very small eyes, thick, relatively hairless tails and make frequent shrill high pitched squeaks. The musk glands on its flanks give it a distinctive smell (BBC, 2006).
Olsen (1984) outlines a method of distinguishing the fecal pellets of shrews from those of other commensal rodents.
agricultural areas, natural forests, ruderal/disturbed, urban areas
The Indian musk shrew (Suncus murinus) is a robust and highly adaptable species. It has a lower metabolic rate than European shrews and is therefore less susceptible to environmental stress. It is found on many islands, in forests or in agricultural land. It is particularly associated with human activity, and this has undoubtedly assisted its geographic spread. The species poses a growing threat as humans continue to facilitate its range expansion. Yang and Zhuge (1989) found that the home range size averaged 1227m2 for male shrews, and 241m2 for females. In Guam, S. murinus nests can be found in open, grassy areas, and beneath or beside large rocks, logs, brush piles and similar materials (Peterson, 1956).
The Indian musk shrew (Suncus murinus) can reach high densities and impact upon a wide range of other species, including plants, invertebrates and vertebrates, either through predation or competition. S. murinus is strongly implicated in the extirpation of several island lizard species (Jones 1993, Rodda & Fritts 1992, Fritts & Rodda 1998). It can damage seeds and young plants by digging for food (pers. obs.). S. murinus can also act as a reservoir for the plague (Duplantier et al., 2005).
The Indian musk shrew (Suncus murinus) may have been deliberately introduced to some areas in an attempt to keep away rats and snakes (Prater, 1947; Murray, 1884; in Taber et al., 1967). S. murinus has been successfully domesticated for use as a laboratory animal in the USA and Japan (Tsuji et al., 1999).
Native range: The Indian musk shrew (Suncus murinus) is assumed to have originated in India. It is now widespread in surrounding areas, from eastern Africa and the Middle East to the west, and Southeast Asia and Japan to the east. This dispersal was mostly made under the influence of human transportation (Sawada, 1995; Ruedi et al., 1996).
Known introduced range: Egypt, Tanzania, Djibouti, Eritrea, Kenya, Somalia, Sudan, Bahrain, Iraq, Oman, Saudi Arabia, Yemen, Kuwait, Madagascar, Mauritius, La Réunion, Comoros, Maldives, Palau, Guam, Northern Mariana Islands, Brunei, Philippines, Japan and Singapore.
Introduction pathways to new locations
Ignorant possession: Due to it's commensal habit, this species is most likely transported unknowingly in cargoes or personal effects.
Road vehicles (long distance):
Local dispersal methods
Boat: Due to it's commensal habit, this species is most likely transported unknowingly in cargoes or personal effects.
People sharing resources (local):
There has been little research into the control of the Indian musk shrew (Suncus murinus) and more research is urgently needed, especially in regard to potential poisons. Very little management work has so far been attempted with this species. Limited studies show this species to be relatively unsusceptible to brodifacoum and 1080 (Morris & Morris, 1991; Bell & Bell, 1996), though it is readily live trapped.
Preventative measures: Rodent-proof structures can exclude shrews (Schmidt, 1994).
Cultural: Mowing around structures may decrease preferred habitat and food for shrews (Schmidt, 1994).
Physical: Shrews can be trapped using mouse traps (snap traps), a small box trap, or pit traps. Pit traps are more useful in assessing the presence or absence of shrews in a particular location, as snap trapping appears to understate the abundance of shrews. Traps can be baited with a mixture of peanut butter and rolled oats. A small amount of bacon grease or hamburger may increase the attractiveness of the bait (Schmidt, 1994). Lee (1997) reported that aluminium live traps caught significantly more S. murinus than Japanese plastic snap traps. Live trapping has been used to successfully eradicate the musk shrew from a two hectare island in Mauritius, although a similar attempt failed on the neighbouring island of Ile aux Aigrettes (25 ha) (Varnham et al. 2002). A study by Seymour and colleagues (2005) suggests that the best hypotheses to explain the failure of the campaign was probably the survival of trap-shy shrews. It is observed that shrews target very specific prey, and are not attracted to conventional rodent baits; standard traps rarely work for shrews (B. Coblentz, pers. comm., 2003). Pitfall traps are often favoured for catching shrews (F.W. Schueler, pers. comm., 2003). As they nest under rocks and logs, grids of boards or other flat objects might be placed (and then uncovered periodically) to entice shrews. It may be possible to use dogs to track down survivors of trapping programmes. On Saipan (where shrews often raid pet bowls) snake traps baited with dog or cat food are used. The snake trap is a modified minnow trap with a flap over each door. The local boonie dogs are accustomed to hunting shrews as a part of their diet and are effective hunters (C. Kessler, pers. comm., 2003).
Chemical: Anticoagulant poisons such as brodifacoum have been used successfully to eradicate rats from many islands, however, insectivores such as the shrew S. murinus are less susceptible to the application of toxins such as brodifacoum or 1080; studies have suggested the toxin would have to be applied at unacceptably high concentrations to kill the animal (Eason et al. 2002, Morris and Morris 1991, in Seymour et al., 2005). Secondary poisoning of birds, which has occurred in the Seychelles for example, suggests that native or endangered birds may face undue risk because of excess use of such toxins (Shah 2001, Thorsen et al., 2000, in Seymour et al., 2005).
Biological: Cats may reduce shrew densities around structures - although they seldom eat them. Owls will consume large numbers of shrews. Mowing grass around structures may increase predation of shrews (Schmidt, 1994).
Although nominally an insectivore, the Indian musk shrew (Suncus murinus) is an opportunistic feeder and in some areas feeds predominantly on plant material (Advani and Rana, 1981). It also eats a wide range of invertebrates, and shrews on Mauritius showed a preference for snails during bait trial experiments (Varnham et al., 2002). A Bangladeshi study found that the diet of S. murinus was composed of 62% animal food (mostly insects), 29% plant food and 9% miscellaneous food items (Sarker and Parveen, 1986). Laboratory research has shown that S. murinus will eat bread, cake, pastry, jellies, peanut butter, boiled rice, boiled potato, boiled egg, and a wide range of insect species (Peterson, 1956). Taber et al. (1967) report that S. murinus can be easily attracted with peanut butter. S. murinus exhibits a definite preference for protein-rich materials in India, with food intake per gram body weight being higher in females than males. Feeding peaks at predawn hours, with a minimum occurring in the afternoon (Balakrishnan and Alexander, 1979b). S. murinus are generally solitary and have a high metabolic rate necessitating frequent feeding. Prey is killed by a characteristic neck bite, and the death-shake is seen when S. murinus feed on earthworms or rats. S. murinus have also been observed hoarding food when a large number of insects was offered (Balakrishnan and Alexander, 1979a).
The Indian musk shrew (Suncus murinus) has no behavioural oestrus cycle and follicular development and ovulation are both induced by mating (Gill & Rissman, 1997). The family Soricidae have retained a number of primitive features including a cloaca and internal male testes (Churchfield, 1990), which makes distinguishing the sexes difficult in some cases.
Average litter size varies geographically with recorded values ranging from 2.1 to 4.7 correlated with female body weight, and number of offspring per litter varies between 1 and 8 (Hasler et al., 1977; Nowak et al., 1983). Females reach sexual maturity at around 35 days (Hasler et al., 1977; Gill & Rissman, 1997). Breeding takes place throughout the year, with females usually bearing two litters per year (BBC, 2006). Chang et al. (1999b) reported that the house shrew in Taiwan is a continuous breeder, with greater activity and intensity occurring in spring and summer. A comparison between breeding populations from Guam and Madagascar showed some significant differences. Shrews from Madagascar had larger litters (average 2.8 young per litter) and shorter gestation periods (29.6 days) than shrews from Guam (2.1 young per litter, gestation 30.3 days). There were also a number of behavioural differences apparent (Hasler et al., 1977). A study on shrews in Guam found that food availability was the primary cue for reproduction in males, with social and photoperiod signals playing a modulatory role (Wayne and Rissman, 1990).
Gestation period of around 30 days, weaned at 15-20 days (Hasler et al., 1977; Gill & Rissman, 1997). Lifespan in captivity ranges from 1.5 to 2.5 or 3 years (Dryden, 1969; E. Rissman, pers. comm.), with one individual living 3.2 years (AnAge, undated).
Reviewed by: Karen Varnham.
Compiled by: Karen Varnham & IUCN/SSC Invasive Species Specialist Group (ISSG)
Last Modified: Thursday, 6 April 2006