Learning how to install pine marten den boxes

Who knew looking for the perfect tree to install a pine marten den box would be so tricky?

This was something that Rowie Burcham, Marten’s on the Move Communications and Engagement Officer, discovered as she joined the rest of the Martens on the Move Team for three days of training in den box installation with Dumfries and Galloway Pine Marten Group. Martens on the Move is a new pine marten project funded by The National Lottery Heritage Fund that is working with local communities and organisations to ensure that pine martens can once again thrive in Britain. Rowie tells us what she learnt…

Why do pine marten den boxes need building and installing?

Pine Martens naturally prefer to shelter and raise their young (kits) in large old trees with suitable cavities, where they are high up enough to protect themselves from predators (such as foxes); where they can be kept warm against the harsh weather; and where the kits can be born and grow in safety. However, the historical woodland clearances that occurred across Britain have meant that older trees with large enough cavities are few and far between. So, during the Martens on the Move project, we aim to install 150 pine marten den boxes across our two Strategic Recovery Areas (SRAs) covering the Scottish/English and Welsh/English borders. These boxes will provide pine martens with a safe and comfortable space to overwinter and rear their kits. As part of the project, we are working with groups such as Men’s Sheds and other community groups to build the boxes… the den boxes we installed in Dumfries and Galloway during our training were built by volunteers at the Glenkens Men’s Shed – Thank You!

So, over three days of walking through glorious woodlands searching for the ideal pine marten trees, installing den boxes, chatting to volunteers and having a good laugh, here’s what I learned.

Branches for the young pine martens (kits)

At about seven to eight weeks old, kits will start to venture outside the den and so it’s important that they have branches near the box entrances for them to climb on to while they grow and gain confidence –as an arboreal species, this is an important skill for them to develop. During this period, kits have been observed (through trail camera footage) falling to the ground and if they are unable to climb back up the tree, there is the chance of predation. To prevent this, picking a tree with branches below the box and leading to the base of the trunk is key.

Look at the bark

Each species of tree has different and identifiable features – from its overall size and shape and  type of leaves to the texture of its bark. As with branches, having a rough trunk helps the kits (who have very small claws at this age) clamber around the tree and den box. It also benefits the adult pine martens. As you can imagine, the coarse texture of an oak or ash tree will provide a much better grip compared to the smooth bark of beech or birch trees.

Setting Up trail cameras

To help us monitor pine marten populations, we set up motion-activated trail cameras facing the entrances of the boxes to capture any wildlife using them. Pine martens are a protected species and anyone working within five metres of a den box requires a licence. For this reason, our cameras need to be at least five metres away from the box for the volunteers to change the batteries and SD cards. However, if the camera is set up much further than this, it may not be activated or record any movement, and we risk losing valuable footage. This means that we’re not just looking for one tree, but two within a set distance from each other. Additionally, the camera will need a clear shot of the den box entrances to capture visual evidence of any kits and the maternal behaviours of the adult.

Prevailing winds

These den boxes might not just be used by pine martens during the breeding season, but also as a denning site during the colder months. To ensure that any martens (and kits) using them are kept warm throughout the year, we place the boxes with their two entrances facing away from the prevailing winds.

It’s a team effort!

Installing den boxes is a 100% team effort! These are heavy items and we want them placed with little damage to the tree. We also want to make sure that our staff and volunteers are safe while installing the boxes and so the following tasks help to keep everyone safe… between our party of five, we took it in turns to carry out these tasks.

• Going up the ladder and setting up the temporary pulley system (which is used to bring the den box up the tree)

• Securing the foot of the ladder

• Guiding the den box from the ground

• Holding and pulling the rope

In total, we installed 11 den boxes across western Dumfries and Galloway on six different properties. Communication and listening to one another was crucial to the successful training and by the time the last box had gone up, our team was able to work efficiently and to identify the perfect trees to install the boxes on. The group even had a little cheer at the end!

 We would like to say a huge ‘Thank You!’ to all the landowners and volunteers who supported us with these installations and we hope that this hard work will help provide Britain’s pine martens with some much-needed denning opportunities.

Rowie Burcham, Martens on the Move Communications and Engagement Officer