What is a footprint tunnel? How the CRT is using them to protect hazel dormice.

For the CRT’s Christmas appeal this year, we are raising funds to help protect one of Britain’s most charming but vulnerable small mammals, the hazel dormouse. 

To do this, we are aiming to raise £6,000 to fund essential habitat restoration and footprint monitoring tunnels across six CRT farms in Herefordshire, Surrey and Dorset, helping to protect and detect dormice before it’s too late. 

But what exactly is a footprint tunnel and how does it help conservation? 

Footprint tunnels are non-invasive survey tools used to detect the presence of dormice by recording their footprints.  

They are usually made of 400mm lengths of 65m square black downpipe. A 500mm length of 9mm plywood serves as the tracking plate, with landing platforms at each end. A strip of thick white card attached to the plywood insert using double-sided sticky tape with an ink made from charcoal and vegetable oil. When a dormouse walks over the ink pad, it leaves footprints on the paper, which can be checked to identify their presence. 

The tunnels are secured horizontally beneath branches in dense shrub areas. Dormice are arboreal, meaning they live in trees, so will naturally travel through the tunnels as they move and forage. 

Hazel Dormouse (Muscardinus avellanarius) Footprints Turnastone Court Farm

How often are the footprint tunnels checked? 

The tunnels are placed in a chosen area where it is thought dormice may be present and placed about 15 to 20 metres apart. It is recommended to have between 30 and 50 tunnels, spaced 15-20m apart, to achieve a good chance of detecting the species if they are present. 

They are surveyed every two weeks over two consecutive months between May and October, providing an 82 per cent chance of detection if dormice are present. Each tunnel captures footprints as dormice pass through, offering a reliable, non-invasive monitoring method. Volunteers can help check them without needing a dormouse licence. 

When we have identified where they are living, we can carefully plan our habitat management to allow them to thrive. 

Where will you put the footprint tunnels? 
 
We’ll place tunnels at: 

Pierrepont Farm and Green Farm in Surrey,  

Bere Marsh Farm and Babers Farm in Dorset  

Awnells Farm and Turnastone Court Farm in Herefordshire 

What habitats will we put the footprint tunnels in? 

We would like to put out tunnels in places where we believe dormice are likely to be present across our farms, particularly those in the south of the country, where dormouse abundance is greater.

Suitable habitat for dormice include hedgerows, scrub, and woodland with a dense and well-connected understory.  

The key thing in terms of habitat (whether woodland, hedge scrub etc) is that there is a variety of different species present, so that there is enough food available at different times throughout the period when dormice are active. This is because different trees, shrubs and other plants flower and fruit at different times. 

Ruth Moss Hazel Dormouse Footprint Tunnel Preparation Awnells Farm

How can you tell you have dormice in the tunnels and not another woodland mammal? 

Differentiating between hazel dormouse footprints and those of other small mammals is essential for using tracking tunnels. Our conservation officer, Ruth Moss, will train our volunteers to do this.  Hazel dormouse footprints are very unique. Their footprints are small, about 1cm wide, with a rounded shape and they have distinctive triangular pads on their feet. The toe pads look similar to the pieces of pie in the Trivial Pursuit game. Footprints of wood mice and yellow-necked mice are composed of little spots rather than triangles. 

How can you help? 

We want to install 250 dormice tunnels across six farms and we need to raise £1,250 to do this. The rest of the money for our £6,000 appeal will go towards creating a shelter belt at Turnastone Court Farm in Herefordshire to form a woodland corridor habitat for dormice to utilise and move between woodland patches. We know they are present in some areas of the farm and want to help them connect to other areas, aiding better gene flow.. The improved habitat will also benefit birds, bats, hedgehogs and other wildlife, creating a healthier, more connected landscape.