Harvest Mouse

How to Survey for Harvest Mice

Why the Harvest Mouse?

The tiny harvest mouse is one of Worcestershire’s least known mammals.

The Worcestershire Biological Records Centre only has 26 records between 1995-2007, so it is almost certainly under recorded!

We want to update the distribution of harvest mice in Worcestershire, and with your help, we can find out where they are clinging on.

What Do I Look For?

The best way to determine the presence of harvest mice, is by finding their nests which are spherical, woven structures.

Breeding nests are around the same size as a cricket ball and non-breeding nests are smaller, more flimsy and are not lined.

Ok, I know what to look for, but what do I do?

Glad you asked! See the list below for step-by-step instructions of how to carry out the survey.

Surveys can be done any time from early November through to end of February, though later surveys run the risk of vegetation being flattened and/or nests destroyed by winter weather.

  1. Look for areas of long grass, reeds, or similar vegetation. Dense grasses or tussocky clumps in wet/dry habitats are good.
  2. Use your hands to gently move the vegetation apart.
  3. In tussocky vegetation, search for nests around the ground level. In tall grasses, look around the stalks.
  4. If you find a nest, check if it’s been built by a harvest mouse or a vole. Harvest mouse nests are woven using the living plant, and will still be attached as you try to remove them. Field vole nests comprise of small, cut pieces of vegetation and are not woven. They are found very close to the ground, and are not found part-way up stems like harvest mice.
  5. If you find a nest, take a photo for verification purposes.
  6. Record your findings on our survey form, even if you didn’t find any nests.
  7. Email your completed survey form and accompanying photos to

For more information and to see an example of suitable habitats, see the below video from the Mammal Society.


Good luck and we look forward to receiving your records!