RSPB Scotland wants to be at the forefront of developing new ways to improve habitats for nature. Sometimes that means trying out surprising things. But few are as unusual as bringing robotic cutters into an ancient forest to help threatened capercaillie populations.  

Capercaillie populations are declining across Scotland, due to a number of factors including low productivity, disturbance and a lack of habitat.  At our Abernethy reserve, we are trialling two innovative management techniques to cut and graze the vegetation in a section of the forest to improve the habitat for capercaillie and other biodiversity.  

The trial started in 2020 and runs for three years, as part of the LIFE 100% for Nature project.  In one of the 200 ha trial plots, we’ve introduced a small herd of cattle for a few months each year for conservation grazing.  The impact of the cows’ trampling and dung helps clear sections of the forest floor of dense heather and helps encourage smaller plants to grow.   

In our other 200 ha trial plot, we’ve enlisted the help of a remote-controlled mower called a Robocutter. From previous smaller-scale trials, we know that cutting can improve the ground-vegetation for capercaillie by increasing the abundance of blaeberry and invertebrate numbers, which are important foods for capercaillie chicks.  

 

We are using a local company, Future Forestry based in Alford, to deliver the robocutting work for us.  The Robocutter mulches the ground-vegetation, stimulating regrowth below the ground.  The machine has a steel head covered in teeth which spins, pulverising vegetation into a mulch. That material can provide a place where blaeberry can seed and regrow. 

To showcase this innovative management technique, we invited a group of 10 stakeholders and land managers to the reserve on 20th October 2021 to see the Robocutter in action! 

 

Our Senior Site Manager, Uwe Stoneman, gave the group a tour of the area where the Robocutter had been deployed in 2020 and compared it with the recent cutting in the 2021 management period.  There are already signs of regrowth of plants like blaeberry and cowberry emerging on the forest floor one year on, compared with the contrast of the dense heather patches that dominated previously.  The cut areas are also full of young pine seedlings, which have been able to germinate because the mulch is an excellent seedbed.  There has been a flush of fungi growing where the Robocutter has been, taking advantage of different conditions to the tall heather.  The management also has knock-on benefits for the smaller creatures in the forest, with evidence of colonisation of cut areas by wood ants and by the very rare narrow headed ant.   

Capercaillie not only rely on plants like blaeberry for an invertebrate food source, but also like a mix of dense cover and open spaces. Thicker vegetation gives chicks somewhere to hide from predators. Open areas are easier for the tiny chicks to move in and allow birds to dry out after wet weather. We’ve seen capercaillie droppings and dust baths (where they clean themselves with sandy soil) within the cut areas so this is a promising sign that they are using these sections of forest already. 

 

L: During the cutting within a dense area of heather-dominated habitat R: One year on from the robocutting, with patches of blaeberry emerging 

Where the Robocutter is particularly beneficial is in cutting a precise area that has been mapped out and programmed into the machine.  This means we can avoid particularly sensitive areas of habitat such as rare narrow-headed ant nests.  The Robocutter can also cover a large area at a time (0.75ha per day on average), cutting and mulching long undergrowth much more quickly, and more precisely, than other methods such as brush cutting.  The mulch that is left behind is also less dense than other cutting methods, and quickly decomposes allowing regrowth to emerge more easily. 

 

The mulch that is left behind after the area has been cut with the Robocutter 

We hope that land managers looking after habitat that is important for capercaillie will also consider innovative vegetation management approaches, like the Robocutter, to improve the amount of good quality habitat for one of the UK’s rarest bird species.  

So… are robots the future for capercaillie?  We’ll have to wait and see what the outcome of our trials are at Abernethy!  Our straw poll at the demo event gave the cattle the win, but we know that cutting and grazing can both be successful ways of improving the special habitat that capercaillie and other biodiversity relies on. 

To find out more, watch our film of the Robocutter at work in the forest.

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