National Harvest Mouse Survey

Written By

Credit: Dulcie Fairweather

On the Red List for Britain’s Mammals, the harvest mouse is classified as Near Threatened in Britain. This means that they are at risk of becoming threatened with extinction in the near future.

Unfortunately, we do not have good estimates of how many harvest mice there are in the wild, so we really have no idea how bad their situation is or what sort of conservation actions should be put in place.

This is why we’ve launched the National Harvest Mouse Survey across the British Isles and Ireland. We’re looking for people across the UK who can get outside and look for harvest mice nests. Surveys do not take long and no prior experience or specialist equipment is required to carry them out.

How to survey for harvest mice

We’ve written a helpful guide which explains exactly how to survey for harvest mice in your area! This is called our project protocol. It includes information on where and how you should be looking, how to identify a harvest mouse nest and how you should conduct your survey. 

Check out the diagram below to see if you’ve found a harvest mouse nest.

How to submit your data

There are a number of ways that you can record data from conducted surveys.

  • Record your data on our Mammal Mapper app.

  • Report your survey findings directly to us via email to science@themammalsociety.org.

  • If you’d rather record your findings on paper or Excel, use you can use our recording template in the ‘useful documents’ section of this page.

When is the next survey happening?

Our third annual National Harvest Mouse Survey will take place between October 2023 and March 2024. Harvest mouse surveys are carried out during these months so as not to disturb breeding harvest mouse nests. Surveys do not take long to carry out but can be as long as you like.

For more information please read our project protocol.

Our timeline this year is as follows:

  • Start by checking if you have a Local Mammal Group. It is likely that they are already involved with the survey and will be able to get you involved with surveying. If no Local Mammal Group exists in your area, get in touch with us and we will see how we can support you.

  • October – March: Survey season starts! During this time training will also be held so you will be ready to hunt for those nests.

  • March 2025 onwards: We will analyse the records and let you know what we have found.

Become a local coordinator

Our National Harvest Mouse Survey relies on local coordinators, who provide information on local events, help to direct surveys and collect survey data. We have a fantastic team of coordinators across the UK who will be joining us again for next season’s survey.

We have some areas without coordinators. If you’re interested in becoming a local coordinator, get in touch for more information on how to get involved.

Useful documents

We have a lot of extra information to help you with your survey, including our risk assessment, instructions on using Mammal Mapper, health and safety and letter to landowners. Please have a look at these before starting your survey.

Frequently asked questions

  • A harvest mouse is Britain’s smallest rodent. If you’d like to learn more about this mammal click here.

  • • Record it on our Mammal Mapper app – this is free to download from your app store.

    • Fill out an online recording form here.

    • Email the team on science@themammalsociety.org.

  • No, the nest survey is non invasive and mice will not be captured or handled. Read more in our survey protocol.

  • No, the survey is taking place over the autumn and winter when nearly all nests will be empty, i.e. brown in colour with a visible exit hole. This is the best time to be able to spot nests without disturbing the animals. However, if you spot a green nest without an exit hole the nest could still be occupied, so record it but try not touch, remove or disturb the nest in any way.

  • We can put you in touch with trainers, coordinators and surveyors in your area. This way you will be able to join a training session and learn exactly how to carry out the survey. The Mammal Society team and coordinators will also be able to help you find surveyors in your area so you do not have to go out on your own.

  • We’d love to know more! We want to work with as many groups already conducting harvest mouse surveys as possible so we can work together to collect data. The aim of our survey plan is to make it as easy as possible for groups already conducting surveys to join in without having to change what they’re doing. Let us know on science@themammalsociety.org.

  • Let us know and we can put you on our mailing lists to forewarn you when regional or national meetings will be held to discuss the result. Fill in this form or email the team on science@themammalsociety.org.

    You can also support the project by donating here. Unlike many organisations, the Mammal Society does not receive government funding so your donations are vital for us to continue our important work.

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