Holnicote Estate, managed by the National Trust across 5,059 hectares of Exmoor National Park, is employing a range of strategies to control deer and grey squirrel populations that pose a risk to its diverse woodlands. These methods include culling, enhancing natural predation, and using sheep's wool and lanolin-based products, with a planned duration of three to five years.
Grey squirrels are a significant threat, stripping bark from trees. The estate has successfully removed around 150 grey squirrels from a damaged area between October 2024 and June 2025, using trained volunteers with low-powered air rifles at fixed bait stations. This approach was adopted after the confirmed presence of pine martens made lethal traps for squirrels no longer permissible.
For deer management, the estate has opted against traditional fencing due to its cost and potential to displace deer. Instead, it uses Trico®, a deer repellent spray, which has shown initial success in reducing roe deer browsing damage to below 20% in Riverlands Wood within the first year. Lethal control is also selectively used to maintain deer populations at sustainable levels, currently around 8 deer per square kilometre.
Further plans include releasing another 10 pine martens into Exmoor National Park within the next year as part of a broader reintroduction scheme, aiming to support natural predation of grey squirrels.