From the survey results over the last 7 years, we can see that there are three particular habitat types where harvest mice thrive in Devon. Cocksfoot grasses, often found on field margins, along footpaths and road verges is by far the most likely place to find harvest mouse nests here, followed by molinia, also known as purple moor grass. This is a heath/moorland specialist which forms large tussocks, perfect for harvest to build nests in. Another stronghold, but far harder to survey, is Phragmites, or common reed, found in wet areas such as around ponds, lakes, estuaries and sewage works.
On this page you will find photos of areas with these plants to help you spot likely places to search for harvest mouse nests. Each photo is of a site where significant numbers of nests were found. The best numbers of nests tend to be on sites that are also south-facing slopes, so if you spot long grass on a south facing slope, it is definitely worth a look!
(All text and photos copyright S.Butcher. Please don’t copy them without written permission.)
Cocksfoot grass (Dactylis glomerata): a tussock-forming tall grass that grows on all soil types. It can reach heights of over a metre and tussocks that are at least a year old are the best for nest building. It flowers between June and September and the seed heads form a distinctive shape with a spur a bit like a cock’s foot. It is suitable for grazing, hay and sileage and is drought tolerant. It grows less tall when very dry, meaning that harvest mouse nests are often found lower down the tussock after dry summers.
Molinia/purple moor grass (Molinia caerulea): a deciduous-tussock forming large grass that grows on wet heathland and areas such as Dartmoor. Although it is grey-green during the summer, by the autumn it is brown and dies back. The most likely tussocks to find nests in are the dense ones with ‘fluffy’ tops. Harvest mice don’t mind living in tussocks surrounded by water as they can bridge between stems by climbing the stems. The insides of the tussocks are often very dry and well-protected,
Common reed (Phragmites australis): a tall grass found in wetlands, growing over two metres tall at times, has hollow stems, slender leaves and is green in summer turning to golden-brown in the summer. It forms dense reed beds that are havens for wildlife, and historically were often used for sewage treatment, or sludge beds. Nests are easiest to find when the plants are on the ground as you pick them up and the nests fall out.
