Pigs and wild boar
Learn more about protecting trees from the domestic pig (Sus domesticus) and wild boar (Sus scrofa).
Wild boar were once native to the UK but became extinct in the wild by the 17th century, largely due to habitat loss and overhunting.
In recent decades, feral wild boar populations have returned to southern England following escapes from farms and deliberate releases. The largest population is in the Forest of Dean, Gloucestershire, where numbers reached an estimated 1,635 animals in 2019. Smaller populations exist in Kent, Sussex, Herefordshire, Devon, and Dorset, as well as localised areas in Wales and Scotland.
Wild boar farming in the England is regulated under the Dangerous Wild Animals Act 1976, while domestic pig welfare is protected by the Animal Welfare Act 2006.
Feral wild boar have no specific legal protection but are covered under general wildlife legislation including the Wild Mammals (Protection) Act 1996 and the Wildlife and Countryside Act 1981.
It is likely there has been significant genetic mixing between wild boar and domestic pigs. Some domestic pig breeds are used for woodland grazing and management. This guidance covers both because they have similar impacts on woodland ecosystems and trees.
- lowland broadleaved woodland (most common)
- wet woodland (frequently found)
- mixed plantation (frequently found)
- wood pasture, parkland and orchards (frequently found)
Rooting behaviour can:
- reduce rank vegetation and bracken cover
- promote new plant growth by uncovering dormant seeds in the soil and provide a seed bed for natural regeneration
However, excessive rooting can mix soil layers. This reduces vegetation cover and leaf litter, increases nitrate concentrations and soil respiration, and decreases the abundance of soil arthropods. High densities can completely remove woodland ground flora, including valued species such as pignut and bluebell.
Rooting damage
- most common sign of domestic pig and wild boar activity
- can damage trees at all stages of growth
- mature trees are vulnerable to fine root and mycorrhizae damage
- high densities can lead to soil structural damage
- concerning for ancient and veteran trees that need stable soil conditions and intact root networks for their longevity and resilience
Rubbing damage
- domestic pigs and wild boar may rub against mature trees, leading to bark damage
- can lead to nutrient deficiencies, disease susceptibility, stunted growth, and tree death
- more likely with domestic pigs where movement is restricted
Wild boar damage can be distinguished from that caused by other animals, like badgers, based on several factors:
- soil disturbance is typically 5 to 15cm deep (compared to badger disturbance which is less than 5cm)
- larger rooted patches
- large snout marks often visible at the edges of the patches
- wild boar hair has distinctive whitish split ends, which can sometimes get caught in fences
Domestic pigs and wild boar are large, powerful animals. They can damage fencing, allowing other species to enter enclosures and cause further damage.
Widespread use
Lethal control: shooting and trapping.
Occasional use
Non-lethal control: stocking rate, stocking density, and timing and pattern of grazing.
In trial or development
Non-lethal control: immunocontraception.
Any control must be conducted in line with animal welfare legislation such as the Wild Mammals (Protection) Act 1996 and the Animal Welfare Act 2006.
Widespread use
Physical exclusion from an area: fencing.
Any control must be conducted in line with animal welfare legislation such as the Wild Mammals (Protection) Act 1996 and the Animal Welfare Act 2006.
Case studies, trials, and scientific research
Forestry England
More information about wild boar in the Forest of Dean.