VWT staff and volunteers check pine marten den boxes

Across four days, ten local volunteers and representatives from National Trust and Natural Resources Wales joined Lucy Nord (Project Officer, Welsh/English border) and Katherine McBride (VWT Carnivore Conservation Officer) to visit the den boxes and record if pine martens are using them for breeding. These den boxes were originally installed in Welsh woodlands during VWT’s Pine Marten Recovery Project and are part of our ongoing monitoring work.  

The pine marten is a protected species under the Wildlife and Countryside Act (1981) and it is illegal to disturb the animal when it is in its den. Therefore, when monitoring the species at our Mid Wales Monitoring Hub, we use thermal imaging cameras to detect heat signatures from the den boxes, making sure we are at least 5m away from the box to avoid disturbing a pine marten that might be inside. A team member quietly approaches the box, continually checking for a heat signature with the thermal imaging camera every few metres, until they can confirm whether the box is in use. If the thermal imaging camera shows a negative heat signature, meaning that the den box is empty, the team will then carefully check for external signs of pine martens, such as claw marks on branches and scats on the lid of the den box. 

Thermal imager cameras can detect the body heat of animals from a safe distance to prevent disturbance.

If a heat signature is detected, trail cameras are installed facing the den boxes to monitor any pine marten activity. The cameras will be checked in approximately one month to change batteries and SD cards and then continue to be monitored until early June. Cameras must always be placed at least 5m away from the den box to avoid the risk of disturbance.

During these four days of monitoring, the volunteers recorded data from 42 pine marten den boxes. This data is important to increase our understanding of pine martens in the area and to monitor their breeding success, movements and behaviour.

Trail camera set up to monitor a pine marten den box.

This work is carried out in April when the kits spend their time solely in the den so that the trail cameras are in place, ready to capture evidence of pine marten presence and record movements and behaviours once the kits are old enough to leave the den.

This spring breeding season monitoring is followed by maintenance checks of the den boxes in the autumn when pine martens are least likely to be using the boxes — we still, however, follow the same protocol of using thermal imaging cameras to make sure that the den boxes are not occupied.

To register your interest in volunteering with Martens on the Move, click here.