Wild boar once roamed across the UK. Despite some now existing in the wild due to various escaped populations, they are still missing from most of their former range. Our work with captive groups at Glen Affric and Dundreggan is showing what an essential role they play in maintaining the Caledonian Forest ecosystem.
Wild boar (Sus scrofa) are the wild-living ancestors from which domestic pigs are descended. They inhabit woodland and scrubland where they live a mainly nocturnal life; foraging during the night and spending the day sleeping in nests on the forest floor. Their diet includes roots and tubers, insects, worms, berries, nuts, bird eggs and small mammals, although plant matter forms about 90% of their total intake.
They are a social species that live in groups of 20 or more, known as sounders. Males (boars) join the group briefly for the breeding season in autumn and the females (sows) give birth to a litter of up to 12 piglets in the spring.
Wild boar were once found throughout much of the UK but became extinct in the 13th century due to over-hunting. Subsequent reintroduced populations were also over-hunted and by the end of the 17th century the species was again extinct. Today escaped captive populations are present in Kent/East Sussex, Dorset, Devon, Gloucestershire, and Dumfries and Galloway, with sightings reported in other counties.
Reintroduction on a large scale would be controversial due to the damage that they can cause to agricultural land, with destruction of crops a big problem on the continent. However, within the Caledonian Forest ecosystem, wild boar serve a very important purpose.
Because of their large size and frequent rooting for food, wild boar have a significant effect on the forest floor. 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.
Our work with wild boar began in 2004 when we became partners in the Giusachan Wild Boar Project, which kept wild boar in an enclosure in Glen Affric. This project fenced in relatively small areas and used high densities of boar.
In 2009 we began a more substantial project; keeping wild boar on our own estate at Dundreggan, because 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. Last year’s 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. The measurements this year support this. 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. This means that we need more boar! We plan to breed our boar later on in the year, so, very excitingly, next year we will have wild boar piglets! We’ll keep you posted on developments.
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