Hazel dormice nest tubes

Nest tubes, similar to those first designed for use with edible dormice (Morris and Temple 1998), are a very useful method for detecting dormouse presence. The numbers of recorded nests or animals should not be used to infer population size.

Correct installation of nest tubes is important to maximise the chances of detection. They should be secured in woody vegetation, selecting areas with the best habitat quality. Short lengths of wire or reusable cable ties work well for tying tubes below branches or into bramble, as it means the tube can be taken down for checking. The tubes are relatively inexpensive and lightweight, so they can be deployed on a large scale: a single surveyor can carry fifty tubes and put them up in half a day. The plastic outer casing is very durable, although the wooden insert may only last a year, depending on rainfall. New inserts are easily manufactured from a sheet of exterior-grade plywood, which should be derived from a sustainable forestry source.

Putting up nest tubes

The tube is suspended below a branch as near horizontal as possible, albeit with the open end lower than the closed end to limit ingress of water. It must be securely attached using coated wire or reusable cable ties to ensure it remains in place.

Tubes should be spaced approximately 15-20 m  apart along a transect, utilising the densest habitat. There is no benefit to decreasing the spacing to less than 10 m apart. Where grids rather than transects are needed to sample several dormouse home ranges, the rows should be at least 75 m apart.

If it is necessary to mark tubes as an aid to relocating them, this should be done unobtrusively, particularly where disturbance by the public is likely. For example, a small strip of tape can be tied to vegetation one metre to the side of a tube: it should be removed when the survey ends.

Where nest tubes cannot be hidden in public areas use an alternative survey method such as footprint tunnels to avoid disturbing dormice.

In woodland

Tubes placed along ride margins and woodland edges maximise detection of dormice. Young plantations can also be surveyed using nest tubes. In mature woodlands there may be few horizontal branches to support nest tubes and dormice may be active mainly in the high canopy, using tree holes for nesting. This is likely to reduce the chance of detection.

In hedgerows

Nest tubes are often easy to place in hedgerows as there are usually suitable horizontal branches in dense vegetation. Tubes should be placed far enough into a hedge to avoid the flail line, or should be removed ahead of any hedgerow management.

In scrub

Shortage of mature trees in scrub habitats means that dormice may readily use nest tubes, especially when cover is reduced at the beginning and end of the active season. In rambling vegetation such as bramble, the tubes should be secured to several stems to ensure they remain level. Markers may be needed to find the tubes later in the season as there can be rapid growth of vegetation.

Timing of visits

Visit in the active season, from mid-late April onwards. Monthly checks will give the best chance of detection. Dormouse nests can be lost or be destroyed by wood mice and yellownecked mice, so it is important to check the tubes regularly.

Removing nest tubes

To preserve the wooden inserts and to avoid leaving plastic in the environment, nest tubes should be taken down at the end of the active season (usually by the end of November). New nests can be made as late as December, so always check for occupancy before taking tubes down. If unsure, err on the side of caution and leave in situ, to be collected later.

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