Taxonomic name: Mus musculus Linnaeus, 1758
Synonyms:
Common names: biganuelo (Dominican Republic), field mouse (English), Hausmaus (German), house mouse (English), kiore-iti (Maori), raton casero (Dominican Republic), souris commune (French), wood mouse (English)
Organism type: mammal Mus musculus (the house mouse) probably has a world distribution more extensive than any mammal, apart from humans. Its geographic spread has been facilitated by its commensal relationship with humans which extends back at least 8,000 years. They do considerable damage by destroying crops and consuming and/or contaminating food supplies intended for human consumption. They are prolific breeders, sometimes erupting and reaching plague proportions. They have also been implicated in the extinction of indigenous species in ecosytems they have invaded and colonised. An important factor in the success of Mus musculus is its behavioural plasticity brought about by the decoupling of genetics and behaviour. This enables M. musculus to adapt quickly and to survive and prosper in new environments. Description
A long tail (60-105mm - approximately equal to its head and body length of 65-95mm), large prominent black eyes, round ears and a pointed muzzle with long whiskers. Adults 12-30 g. Wild mice are commonly light brown to black; belly fur white, brown, or grey. Colour of tail also lighter below than above. Occurs in:
agricultural areas, coastland, natural forests, planted forests, range/grasslands, riparian zones, ruderal/disturbed, scrub/shrublands, urban areas Habitat description
As commensal animals, house mice (Mus musculus) live in close association with man — in his houses, outbuildings, stores, and other structures. Where conditions permit, feral mice may be found in fields, along watercourses, and in other places where vegetation is dense enough to afford concealment. These feral animals make runways through the grass, or they may utilize runways made by cotton rats and other meadow-inhabiting species. In the agricultural regions where irrigation is practiced house mice often are found in the vegetation along irrigation ditches, sometimes sharing common runways with native mice (Mammals of Texas-House mouse). Notes
The taxonomy of the genus Mus is still not entirely clear and the last 30 years have seen a continuing reduction in the number of species recognised and a rearrangement of the phylogenetic tree. The confusion arises because of the gross morphological similarity of many Mus species, many of which are only (relatively) distantly related and the phenotypic plasticity within the various species themselves. It is now accepted that the genus Mus is actually comprised of 4 subgenera - Pyromys, Coelomys, Mus, and Nannomys - containing, in total, approximately 40 species plus an unknown number of subspecies (Nowak, 1991). Silver (1995), drawing on detailed genetic analysis, lists 8 true species in the Mus subgenus plus 4 morphologically and biochemically distinct Mus musculus subspecies that together form an M. musculus species group. These are Mus mus musculus, M. m. domesticus, M. m. castaneus, and M. m. bactrianus. He relegates M. m. molossinus, found throughout Japan, to faux-species status as it has been found to be a hybrid between M. m. musculus and M. m. castaneus. Furthermore, the genetic evidence supports the Indian subcontinent as the centre of radiation for the M. musculus species group, M. m. bactrianus being the founder population. The members of the M. musculus group would have occupied non-overlapping ranges within the Indian subcontinent until Neolithic human population expansion and migration approximately 10,000 yrs BP facilitated their dispersal. The two species found in Europe - M. m. musculus and M. m. domesticus - accompanied humans migrating into the area approximately 4,000 yrs BP. It is predominantly these two species that have become invasive throughout the world, primarily aided by past European colonial expansion. Geographical range
Native range: Native to the Indian subcontinent.
Known introduced range: The house mouse (Mus musculus) has accompanied humans to, and colonised, tropical, temperate, semi-desert, desert, and subantarctic regions throughout the world. Introduction pathways to new locations
Aircraft:
Ignorant possession:
Military:
Road vehicles (long distance):
Seafreight (container/bulk):
Local dispersal methods
Boat:
Escape from confinement:
Natural dispersal (local):
Off-road vehicles:
Road vehicles: Management information
House mice (Mus musculus) are controlled by poisoning, fumigation, trapping and repellents. Thirty eight percent of mouse eradication attempts on islands worldwide have failed (17 out of 45 attempts), but there doesn't seem to be a consistent simple operational explanation for these failures. Eradications should be attempted provided sufficient planning and preparation has taken place to rule out failure due to operational errors or factors that can be controlled for. Factors to consider in order to maximise the likelihood of success include:
- Will the chosen poisoning method allow every mouse on the island access to poison?
- Take genetic samples prior to the eradication attempt. This allows the distinction to be made between eradication failure and a re-invasion and also can be used to determine sub-species.
- Consider the effects of other mammals. Will they prevent mice accessing poison?
- Will the mice eat the bait? Consider bait trials to check for poison palatability and cereal aversion.
- Are there areas which may require extra poison? Dense grassland can support very high numbers of mice and may require more poison than forest areas (MacKay et al., 2007).
Preventative measures: House mice are able to stow away in very small spaces so there is a constant threat of invasion or reinvasion. Visitors to areas that are at risk of mouse invasion should be encouraged to check all baggage and pockets for mice before heading to such places. Mouse free areas that are considered at risk of invasion should implement a programme of regular monitoring to identify mouse invasions early. Chemical: House mice have been successfully eradicated from 28 islands worldwide. In all these cases some form of anticoagulant poison was used (MacKay et al., 2007). Brodifacoum was the most commonly used poison, other successful attempts used pindone, warfarin, bromodiolone and floccoumafen. Brodifacoum is a very widely used toxin but there are some concerns about it building up in ecosystems (Hoare and Hare, 2006). Fisher (2005) discusses the susceptibility of mice to a variety of anticoagulant poisons; Morriss et al. (2008) updates this study by investigating factors that affect the palatability of different baits to house mice and rat species. Biological: Virally vectored immunocontraception using a modified murine cytomegalovirus (MCMV) is being developed in Australia for the control of outbreaks of M. Musculus in the grain-growing regions of Australia (Arthur et al. 2005). Integrated management: The abundance of M. Musculus will increase dramatically where a significant number of rats are removed from an area, perhaps due to an improved food supply or a release from predation pressure (Caut et al. 2007, Witmer et al. 2007). It is important to attempt to remove mice at the same time as rats to prevent large populations of mice appearing following rat removal. Nutrition
Wild mice eat many kinds of vegetable matter, such as, fleshy roots, leaves, and stems. Insects and some meat may be eaten when available. Commensal mice feed on any human food that is accessible, as well as paste, glue, soap, and other household materials. Cereals are preferred to foods containing higher proportions of fat or protein. A large part of the water requirement of mice is met by the moisture content of their food as they have the ability to concentrate their urine and this has enabled them to colonise semi-desert areas. Mice on a seed diet of 12% protein can survive without free water, but above this level of protein require 3-13 g water per day. Reproduction
Placental. Sexual. Endogenous reproductive cycle most likely modulated by nutrition and, possibly, population density.
15-150+ young per female adult per year, depending on conditions. Females as young as 5 weeks can breed. The pre-independence mortality rate is typically 60-70%. Population densities range from 10 per sq metre for commensal populations to 1 per 100 sq metres in feral populations. Given ideal conditions populations can errupt spectacularly and numbers can exceed 200,000 per hectare.
While favourable conditions (e.g. nutrition) determine reproduction in commensal populations, free-living (feral) populations are seasonal breeders, and reproduction is probably influenced by a combination of day length and nutrition
(Pillay, N., pers. comm., 2004). Lifecycle stages
Depending on prevailing environmental conditions, house mice occur alone, in pairs, in small family parties, or several families co-exist at very high densities
(Pillay, N., pers. comm., 2004). Breeding takes place throughout the year in laboratory, most commensal, and some wild populations. The oestrus cycle is 4-6 days, with oestrus lasting less than one day. The oestrus cycle stops during lactation except for one oestrus 12-20 hours postpartum. Gestation period is 19-21 days, although this may be extended by several days if the female is lactating. There are usually 5-10 litters per year, depending on conditions, but up to 14 may be produced. Litters range from 3-12, but usually consist of 5-6, young. Newborn mice weigh around 1 g, are naked except for short vibrissae, and their eyes and ears are closed. They are fully furred after 10 days and by 14 days old their eyes and ears are open, and their incisor teeth have erupted. The young are weaned and start to leave the nest at 20-23 days old, weighing around 6 g, and can reach sexual maturity at 5-7 weeks. In the wild mice rarely live longer than 18 months. Captive mice live 2 years on average although there are records of some individuals living up to 6 years. This species has been nominated as among 100 of the "World's Worst" invaders Reviewed by: Major update under progress
Prof. Neville Pillay
School of Animal, Plant & Environmental Sciences
University of the Witwatersrand South Africa.
Compiled by: Ezra Barwell, School of Geography and Environmental Science, University of Auckland, New Zealand & IUCN/SSC Invasive Species Specialist Group (ISSG)
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Last Modified: Tuesday, 29 August 2006
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