Wild boar

Since 2009 we have been keeping a captive herd of wild boar on our Conservation Estate at Dundreggan and prior to this we were partners in the Giusachan Wild Boar Project in Glen Affric.

Because of their large size and frequent rooting for food, wild boar have a significant effect on the forest floor and so within the Caledonian Forest ecosystem, wild boar serve a very important purpose. Through disturbing the soil, they create ideal conditions for germination of seedlings, especially Scots pine. They can also help to disperse seeds, through pushing them into the soil. One of their most useful functions, and the reason that we are particularly interested in the species, is that they eat bracken, whereas other species are not able to digest it. They also dig it up for bedding material and grub up the underground rhizomes which store starch during the winter. This stops it spreading across the forest floor and preventing the growth of seedlings.

The Giusachan Wild Boar Project fenced in relatively small areas of land and used high densities of boar, to monitor their impact on natural regeneration. Our Dundreggan project is a much more substantial one; we wanted to examine at the impact of keeping lower densities of boar in a larger area. We fenced 12 Ha and gave the boar access to one half of the area for two years, before transferring them to the second half in September 2011. The rational was that the bracken had been sufficiently reduced and the ground conditions were ideal for seedling regeneration, so if we kept the animals there any longer they could root up tree seedlings, either deliberately or inadvertently.

At the end of August each year we measure bracken height and density: in the enclosure where the boar are currently, where they were previously, and outside the fence at set monitoring points. The 2012 and 2013 figures indicated that we had been a little hasty in moving the boar from the first half of the enclosure, as the bracken was showing signs of rapid recovery. Although there are areas where the boar have had a significant and lasting effect and there is a lot of natural regeneration of birch, plus smaller amounts of bird cherry & Scots pine, on average the bracken in the initial area has almost fully recovered. Visits to a neighbouring estate with John Parrot of Coille Alba, who is using Tamworth pigs to control bracken and encourage tree regeneration, have shown that keeping boar at densities of about 1 boar per Ha for periods longer than two years will not significantly damage tree seedlings. Our new plan is therefore to keep the boar in the second half of the enclosure for longer than two years, and we also need to re-introduce them into the first half. 

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