The House Mouse (Mus musculus)

 

The house mouse (Mus musculus) is a native rodent species in Great Britain. It is regarded as a common species, and is listed as being of ‘least concern’ by the IUCN Red List. Some individuals have been domesticated as pets, while others are used as laboratory mice which are advancing science throughout the world. This page has been set up to raise awareness and to increase our understanding of the distribution of the house mouse in Cumbria. We would like you to get involved in recording house mice in your neighbourhood!

Submit Records

Ecology

The house mouse is nocturnal, and frequently lives in a construction of underground tunnels, or within human houses, garages, barns, or sheds.  They rarely inhabit woodland due to competition with other small mammals (PTES). It is their association with humans that has allowed them to spread throughout the world, occupying a range of our domestic buildings, and feasting upon our food supplies. House mice can have a varied diet, but frequently consume grain, fruit, and occasionally invertebrates. They will generally eat any form of human food where it is available. If food is scarce, mice can search an area as large as 200m2, but when food it relatively common their range can be as small as 5m2 (PTES). They can be commonly seen throughout the year especially in breeding seasons when numbers are high or during hibernation periods where they are more likely to enter our buildings and associated structures.


Males are territorial with one or two dominating in highly abundant areas. They can frequently fight to defend their territory and maintain their breeding partners. Females can have up to ten litters a year with approximately four to eight young (RSPB). They have a relatively short gestation period of 19 to 21 days, and the young are weaned for around two weeks. Typically a female produces approximately 40 young during her lifetime. The average lifespan of a house mouse is 18 weeks (British Wildlife Centre), but an individual can survive for up to 18 months in the wild. Overall, the British population is thought to have been stable for the last 25 years with the breeding population estimated to be 5,400,000 individuals (PTES).

Distribution Map

The distribution map shows the number of tetrads containing house mouse records before 2000 (black outlines) and after the year 2000 (pink filled squares). The map suggests that the records we have are largely from lowland areas, with a clear ring around the Lake District National Park and a clear avoidance of the Pennines. It could be that this is because of where recorders live or visit, and not because of where the house mouse is found.

There are only 19 tetrads with data post 2000 and 30 tetrads with records before 2000. In total the CBDC database has 84 records of the house mouse in Cumbria. The majority (49) of these records were made before the year 2000 by 29 recorders (excluding some recorders whose identity is unknown). In contrast, 35 records were made after the year 2000 by 16 recorders. We hope that any records you submit will add to this total and that this will provide us with a better understanding of the house mouse distribution within Cumbria.

Grey Square Challenge

The map shows the hectads (black outlined squares) which have records after the year 2000. The number inside the square represents the number of house mouse records we have on the CBDC database. We hope to increase the number of house mouse records in these hectads, and also increase the number of hectads we have data for. Your records will add valuable information to this map which will help us to target appropriate areas to increase our understanding of the house mouse distribution.

How to identify the house mouse?

Features of a house mouse:
• Dull brown-grey coloured fur.
• It has a length of up to 10cm.
• A long almost hairless tail which is often the same length as its body (up to 10cm). The tail tends to be thicker than other species.
• Small rounded ears that are more prominent than other species. They can be up to 1.cm long (British Wildlife Centre).
• A pointed snout.

How to identify similar species?

A comparison between mice, voles and shrews (The Woodland Trust):
• Mouse: very large eyes, long tail, very large ears, pointed snout.
• Vole: small eyes, short tail, small ears, rounded snout.
• Shrew: small eyes, short tail, small ears, pointed snout.

For more information please download:

- Identification Guide (.PDF)
- House Mouse Info (.PDF)

Submitting a house mouse record

To make a record valuable to us we need to know five main points:
• WHO spotted it?
• WHAT was it?
• WHERE was it? - (a grid reference and location name is preferred)
• WHEN was it spotted?
• HOW many were there?

All small mammal records submitted using this page or will be sent immediately to John Martin for verification until further notice. John is our Cumbria referee for mammals and will be happy to look at any evidence of house mice. He will also verify any mammal records submitted on iRecord.

It would be great if you could include a photograph or other piece of evidence with your record. Ideally, a clear photograph of the head, upperside of the body, and underneath (ventral side) would be useful for identification purposes, however any evidence you have would be highly appreciated.

Please use the form below to submit your house mouse records. If you would prefer to email us your photos or videos please contact us on house.mouse.enquiries@gmail.com.

     

    References:

    British Wildlife Centre. 2012. Available at: https://www.britishwildlifecentre.co.uk/planyourvisit/animals/housemouse.html [Accessed 03/08/2017].
    Cumbria Wildlife Trust. Available at: http://www.cumbriawildlifetrust.org.uk/ [Accessed 03/08/2017].
    Musser, G., Hutterer, R., Kryštufek, B., Yigit, N. & Mitsain, G. 2016. Mus musculus. (errata version published in 2017) The IUCN Red List of Threatened Species 2016: e.T13972A115117618.
    People’s Trust for Endangered Species. 2017. Available at https://ptes.org/get-informed/facts-figures/house-mouse/ [Accessed 03/08/2017].
    The Royal Society for the Protection of Birds. Available at: https://www.rspb.org.uk/birds-and-wildlife/bird-and-wildlife-guides/a-z-of-a-wildlife-garden/atoz/h/housemouse.aspx [Accessed on 03/08/2017].
    The Woodland Trust. Available at: https://www.woodlandtrust.org.uk/blog/2017/07/types-of-uk-mice/ [Accessed 03/08/2017].

    Cumbria Biodiversity Data Centre

    The Cumbria Biodiversity Data Centre at Tullie House Museum, Carlisle keeps wildlife information for the county of Cumbria. Tullie House Museum, in its role as a local natural history museum, has collected and disseminated records of wildlife in Cumbria since its inception in 1893. From the early 1990s the Museum has developed a computerised database of species and habitat records in Cumbria and has taken the central role in providing a local biodiversity data service for the county. This role was restyled as Cumbria Biodiversity Data Centre (CBDC) in 2010, a not-for-profit organisation hosted by Tullie House Museum and advised by local stakeholders.
    Cumbria Biodiversity Data Centre
    Cumbria Biodiversity Data CentreThursday, October 15th, 2026 at 11:20pm
    There are still places on the CHEGD (waxcap and allies) workshop on Sunday 1st November at Plumgarths. If you have some recording experience, this might be of interest. Find out more and sign up:
    https://www.ticketsource.com/cumbria-ecoskills/chegd-fungi-id/e-pmdpqp

    An opportunity to find out more about ancient grasslands!
    Cumbria Biodiversity Data Centre
    Cumbria Biodiversity Data CentreThursday, October 15th, 2026 at 6:55am
    Following up from our last post on the Harlequin ladybird, we thought you might like to see the larval stage which might not be as familiar as the adult. Excellent aphid eaters!
    Cumbria Biodiversity Data Centre
    Cumbria Biodiversity Data CentreThursday, October 1st, 2026 at 1:23am
    Over the next month, you might see more ladybirds coming indoors - especially if you live in more urban areas of Cumbria like Carlisle and Kendal. While native ladybirds will over-winter in garden sheds, leaf litter and crevices in woody plants or fences, the non-native Harlequin (Harmonia axyridis) is looking for somewhere a little warmer to spend the winter diapause and will enter houses to congregate in corners. These ladybirds are originally from Asia so need drier and warmer conditions than the native species.

    The Harlequin is very variable - hence the name. The two examples shown here were collected at the same time in the same place! Some colour patterns can look very similar to the native species but generally Harlequins have brown legs and undersides while native species tend to have black legs/underside. Harlequins tend to be quite large too compared to the more variable sizes seen in the 45+ native species.

    Over-wintering ladybirds won't do any damage and shouldn't pose a problem wherever you find them. But if you do find some in your home and they have brown legs, you can be confident that they are the Harlequin. Do record any ladybirds that you see so we can better understand the key locations of Harlequins across Cumbria and how they might be interacting with the natives.

    And if you want to see a plentiful number of Harlequins this month, Mayor's Drive near Bitts Park in Carlisle is usually a good spot.
    Cumbria Biodiversity Data Centre
    Cumbria Biodiversity Data CentreWednesday, September 23rd, 2026 at 4:57am
    Cumbria has over 1500 County Wildlife Sites, many on private land. We are working with @CumbriaWildlifeTrust to provide free surveys of these sites so we can understand their condition and help guide landowners to find management advice and support.

    Find out more about County Wildlife Sites in general and across Cumbria using these resources - and contact the Cumbria County Wildlife Sites Project if you think you have a site and would welcome a survey.

    https://www.cumbriawildlifetrust.org.uk/wildlife/county-wildlife-sites
    https://www.gov.uk/government/publications/local-sites-and-nature-conservation/local-sites-and-nature-conservation
    Or the LWS Hub: https://www.localwildlifesites.org/
    Cumbria Biodiversity Data Centre
    Cumbria Biodiversity Data CentreWednesday, September 16th, 2026 at 1:12am
    As well as the excellent Plantlife resources and Waxcap Watch, CBDC has two upcoming waxcap training sessions - Thursday 8th October and Sunday 1st November. We're finalising details but do let us know if you would like more information/have priority booking by completing our expressions of interest form:
    https://docs.google.com/forms/d/e/1FAIpQLSe5JQ99XCSMMIyUX641NL8EqGz6gXH4C2hItqp9EFL-iFXhKw/viewform?usp=publish-editor
    Cumbria Biodiversity Data Centre
    Cumbria Biodiversity Data CentreMonday, September 14th, 2026 at 5:51am
    It is apple season! The apple harvest looks good again this year - albeit with possibly smaller apples than usual. Traditionally managed orchards are good sites for biodiversity but their location and condition in Cumbria are not well understood. If you manage a traditional orchard, tell us about it. Do get in contact if you would be willing to share information about your orchard.