Managing mammals in the landscape
Source: gov.uk (2025-10-30)

Learn about the management options to protect trees against mammal damage, including: enhancing natural predation, fencing, tree guards, immunocontraceptives, lethal control and non-lethal control.

While many of these methods have been extensively tested and proven effective, not all methods are suitable for every situation.

Landowners and managers should carefully consider factors such as:
- landscape impact, especially in protected or heritage areas
- existing public access
- potential risks to the public or non-target species
In all cases, you must comply with local rules and regulations.

Enhance natural predation

Nest (or den) boxes

Associated species or groups of species:
- grey squirrel (https://www.gov.uk/guidance/protecting-trees-from-mammal-damage-technical-guidance/grey-squirrel)
- small rodents (https://www.gov.uk/guidance/protecting-trees-from-mammal-damage-technical-guidance/small-rodents)
Some species, such as pine martens, common kestrels, and owls, use cavities in trees for nesting, denning or roosting. Due to the historical woodland management removing mature trees, natural tree cavities may be lacking in many landscapes.

Installing nest (or den) boxes can help mitigate this loss by mimicking natural tree cavities. This should only be a short-term solution, future mature trees should be retained to provide more naturalistic habitat in the long-term.

Supporting populations of these native predators increases biodiversity and promotes natural predator-prey relationships. Evidence suggests that pine martens may help control populations of invasive grey squirrels, while kestrels and owls are important predators of small rodents.

Do not use lethal traps to manage grey squirrels in areas where grey squirrels and pine martens coexist.

Additional information

Managing forest and woodlands for pine martens (https://www.vwt.org.uk/wp-content/uploads/2015/04/Pine-Martens-and-Forest-Management-Leaflet.pdf) from The Vincent Wildlife Trust.

Controlling grey squirrels in forests and woodlands in the United Kingdom (https://www.forestresearch.gov.uk/publications/controlling-grey-squirrels-in-forests-and-woodlands-in-the-uk/)from Forest Research.

Raptor perches

Associated species or groups of species:
- grey squirrel (https://www.gov.uk/guidance/protecting-trees-from-mammal-damage-technical-guidance/grey-squirrel)
- small rodents (https://www.gov.uk/guidance/protecting-trees-from-mammal-damage-technical-guidance/small-rodents)
Installing raptor perches or leaving standing dead trees when clear-felling can help manage grey squirrels and small rodents by increasing the presence of birds of prey in an area. These elevated perches provide vantage points that allow raptors to hunt more efficiently and naturally control these mammal populations.

Reintroduction or range expansion of predator species

Associated species or groups of species: grey squirrel (https://www.gov.uk/guidance/protecting-trees-from-mammal-damage-technical-guidance/grey-squirrel)

Recent research by the Gloucestershire Raptor Monitoring Group shows that northern goshawks are predators of grey squirrels in the UK. A 2023 study, published by the Royal Forestry Society (https://rfs.org.uk/wp-content/uploads/2023/06/QJf-Featured-Article-by-Anna-Field-Apr-2023-Goshawk-as-predators-of-grey-squirrel.pdf) suggests that the northern goshawk breeding season coincides with the time when young grey squirrels leave their dreys.

The research indicates that management strategies that could help naturally manage grey squirrel populations include:
- reducing disturbance to northern goshawks
- encouraging their colonisation of woodlands
- providing stands of conifers away from public footpaths for nesting
However, the evidence does not demonstrate a link with reduced tree damage, so it’s not known if goshawk alone can manage the impacts of grey squirrels.

Additionally, in Ireland, the range expansion of pine martens has been linked to a decline in grey squirrel numbers (https://link.springer.com/article/10.1007/s10531-014-0632-7), partly due to predation. This expansion has been driven by increased habitat availability and legal protection.

Additional information

Managing forest and woodlands for pine martens (https://www.vwt.org.uk/wp-content/uploads/2015/04/Pine-Martens-and-Forest-Management-Leaflet.pdf) from The Vincent Wildlife Trust.

Lethal control

This section covers:
- shooting (#shoot)
- trapping (#trap)
- poisoning (#poison)
- ferreting (#ferret)
Shooting

Associated species or groups of species:
- Eurasian beaver (https://www.gov.uk/guidance/protecting-trees-from-mammal-damage-technical-guidance/eurasian-beaver)
- grey squirrel (https://www.gov.uk/guidance/protecting-trees-from-mammal-damage-technical-guidance/grey-squirrel)
- rabbits and hares (https://www.gov.uk/guidance/protecting-trees-from-mammal-damage-technical-guidance/rabbits-and-hares)
- deer (https://www.gov.uk/guidance/protecting-trees-from-mammal-damage-technical-guidance/deer)
- pigs and wild boar (https://www.gov.uk/guidance/protecting-trees-from-mammal-damage-technical-guidance/pigs-and-wild-boar)
In England, shooting is an established method for the lethal control of certain wild, feral, and non-native mammals, particularly when other management strategies are ineffective or impractical. Shooting is subject to strict regulations to ensure it is carried out humanely and legally. You can be fined or imprisoned for shooting certain species illegally or causing unnecessary suffering to an animal.

To acquire or possess a shotgun, rifle, or certain categories of air weapon, you must hold a valid firearms certificate (https://www.gov.uk/find-licences/shotgun-and-firearm-certificates) of the appropriate type issued by the police. In some cases, you may also require a specific wildlife licence (https://www.gov.uk/guidance/wildlife-licences) to shoot species that are legally protected.

It is crucial to ensure that you are familiar with wildlife protection laws and specific rules and regulations applicable to your location, including:
- which species you intend to legally shoot
- when you can shoot them
- what equipment you can use
The effective control of deer within woodlands requires careful planning to facilitate safe and humane culling. When creating new or restructuring existing woodlands, consider:
- incorporating open spaces such as rides and glades to improve visibility and access
- strategic placement of high seats or hides
Additional information

Guide for Firearms Licencing Law (https://www.gov.uk/government/publications/firearms-law-guidance-to-the-police-2012) from the Home Office.

Deer stalking code of practice (https://basc.org.uk/deer/advice/deer-stalking-code-of-practice/) from the British Association for Shooting and Conservation (BASC).

Information on the management of wild boar (https://basc.org.uk/deer/wild-boar/) from BASC.

Best practice guide to shooting wild boar in England and Wales (https://www.wild-boar.org.uk/pdf/WildBoar_shooting.pdf) from the Deer Initiative Partnership.

Best practice guides to wild deer management (https://thedeerinitiative.co.uk/guides-landing-basc/) from the Deer Initiative Partnership.

Shooting – rights of way and access in England and Wales (https://basc.org.uk/firearms/firearms-use/shooting-rights-of-way-and-access-england-wales/) from the Deer Initiative Partnership.

Guidance on how to control European rabbits on your property through shooting or other lethal control methods (https://www.gov.uk/guidance/rabbits-how-to-control-numbers) from Natural England.

Apply for a licence to shoot deer during the closed season or at night (https://www.gov.uk/government/publications/deer-apply-for-a-licence-to-shoot-them) from Natural England.

Wild deer best practice guidance for Scotland (https://bestpracticeguides.scot/) from NatureScot.

Controlling grey squirrels in forests and woodlands in the UK (https://cdn.forestresearch.gov.uk/2019/12/ukfstn022_m7ldper.pdf) from Forest Research.

Trapping

Associated species or groups of species:
- Eurasian beaver (https://www.gov.uk/guidance/protecting-trees-from-mammal-damage-technical-guidance/eurasian-beaver)
- grey squirrel (https://www.gov.uk/guidance/protecting-trees-from-mammal-damage-technical-guidance/grey-squirrel)
- small rodents (https://www.gov.uk/guidance/protecting-trees-from-mammal-damage-technical-guidance/small-rodents)
- rabbits and hares (https://www.gov.uk/guidance/protecting-trees-from-mammal-damage-technical-guidance/rabbits-and-hares)
- pigs and wild boar (https://www.gov.uk/guidance/protecting-trees-from-mammal-damage-technical-guidance/pigs-and-wild-boar)
Trapping for lethal control is commonly classified into 2 categories:

1. Live trapping

Live trapping involves capturing an animal alive and uninjured, with the intention of culling or translocating it later. Various catching methods can be used to safely confine an animal, including:
- drop nets
- cage trap
- panel traps
- tunnel traps
- corral traps
The aim is to ensure the animal remains alive and unharmed until it can be humanely dealt with.

2. Lethal (or kill) trapping

Traps that are specifically designed to directly kill the animal quickly, such as spring traps. Any spring trap used must be approved for the target animal, in accordance with the Spring Trap Approval (England) Orders of 2018, 2021, and 2023 (https://www.legislation.gov.uk/uksi/2018/1190).

The use of these traps must follow strict protocols, including:
- setting them only during the appropriate season
- pre-baiting to effectively attract the target species
- incorporating exclusion mechanisms to prevent the capture of non-target animals
When conducting grey squirrel trapping in areas where red squirrels or pine martens are also present only use single-capture cage traps (https://cdn.forestresearch.gov.uk/2019/12/ukfstn022_m7ldper.pdf).

Trapping is generally considered to be very labour intensive, as traps must be inspected at least once per day by a competent individual who is well trained and experienced. Trapping can be effective for dealing with specific individual problem animals or small groups (https://www.nature.scot/doc/naturescot-research-report-1226-trapping-feral-pigs-corral-traps-and-drop-nets-possible-population) in specific areas or sites. However, it is more challenging to use this approach to control the whole population of a widely spread species.

Additional information

Pilot study exploring the use of corral traps and drop nets to trap wild boar in Scotland (https://www.nature.scot/doc/naturescot-research-report-1226-trapping-feral-pigs-corral-traps-and-drop-nets-possible-population) from NatureScot.

Licence to trap edible dormice in England (https://www.gov.uk/government/publications/edible-dormice-licence-to-trap-them/edible-dormice-licence-to-trap-them-cl02) from Natural England.

Guidance on how to trap Eurasian beavers (and other mammals) humanely (https://www.gov.uk/guidance/badgers-beavers-otters-and-pine-martens-how-to-trap-humanely) from Natural England and Defra.

Controlling grey squirrels in forests and woodlands in the United Kingdom (https://www.forestresearch.gov.uk/publications/controlling-grey-squirrels-in-forests-and-woodlands-in-the-uk/) from Forest Research.

Poisoning and gassing

Associated species or groups of species:
- small rodents (https://www.gov.uk/guidance/protecting-trees-from-mammal-damage-technical-guidance/small-rodents)
- rabbits (https://www.gov.uk/guidance/protecting-trees-from-mammal-damage-technical-guidance/rabbits-and-hares)
Rodenticides have historically been used to manage mice and vole populations in forestry. However, their use, especially on a large scale, can pose risks to people, pets, and other non-target species. As a result, many rodenticides are being phased out.

For example, Warfarin, once widely used in the UK, is now banned for domestic use due to concerns about its environmental impact. Additionally, as of January 2025, the use of second-generation anticoagulant rodenticides (SGARs), including those containing bromadiolone and difenacoum, is prohibited in open areas and waste dumps (https://bpca.org.uk/test-news/crru-uk-ending-sgar-use-away-from-buildings/277174).

It is legal to gas European rabbits in their burrows with either sodium cyanide or aluminium phosphide. However, actions must comply with the Control of Substances Hazardous to Health Regulations (COSHH) 2022 (https://www.legislation.gov.uk/uksi/2002/2677/regulation/7). Gassing must only be carried out by trained personnel to ensure safety and proper application.

Additional information

Details of the individual rodenticide products authorised for use in the UK (https://www.hse.gov.uk/biocides/uk-authorised-biocidal-products.htm) from the Health and Safety Executive.

Information sheet on the gassing of European rabbits and other vertebrate pests (https://www.hse.gov.uk/pubns/ais22.htm) from the Health and Safety Executive.

Ferreting

Associated species or groups of species: rabbits (https://www.gov.uk/guidance/protecting-trees-from-mammal-damage-technical-guidance/rabbits-and-hares)

Domesticated ferrets can be released into a burrow system (or warren) to drive European rabbits out. The rabbits can then either be captured in nets placed over the burrow entrances or shot as they leave.

Additional information

Guidance on controlling European rabbits in England (https://www.gov.uk/guidance/rabbits-how-to-control-numbers) from Natural England.

Non-lethal control

Stocking rate, stocking density, and timing and pattern of grazing

Associated species or groups of species:
- pigs and wild boar (https://www.gov.uk/guidance/protecting-trees-from-mammal-damage-technical-guidance/pigs-and-wild-boar)
- livestock and European bison (https://www.gov.uk/guidance/protecting-trees-from-mammal-damage-technical-guidance/livestock-and-european-bison)
- horses and ponies (https://www.gov.uk/guidance/protecting-trees-from-mammal-damage-technical-guidance/horses-and-ponies)
Continuous, year-round grazing is often unsuitable. Instead, seasonal or intermittent grazing may be required. To manage grazing effectively, develop a grazing management plan and keep accurate, up-to-date records of both stocking rate and stocking density.

Stocking rate: the number of animals that an area of habitat can support over the course of a year.

Stocking density: the number of animals on an area of land at any one time.

The grazing impact of different livestock species varies. The standard method for measuring and comparing grazing impact is through the Livestock Unit (LU) – where a cow and calf together are typically considered 1 LU, and other animals are assigned relative values based on their grazing intake (https://www.fas.scot/downloads/tn686-conservation-grazing-semi-natural-habitats/). Grazing pressure can be quantified using Livestock Units per hectare (LU/ha), helping you to assess and adjust stocking levels and grazing patterns as needed.

For conservation grazing in woodland pasture and parkland (https://woodlandwildlifetoolkit.sylva.org.uk/advice-types-broadleaf) in England, the recommended stocking density is typically between 0.1 and 0.5 LU/ha. Grazing at densities that mimic natural populations encourages natural regeneration and a more diverse and structurally complex vegetation pattern.

Autumn is the most suitable season for livestock grazing in woodland, because biomass will be at its peak, provided it has not been grazed in summer. Alongside controlled grazing, you should assess the potential impact of deer or other herbivorous mammals on your woodland (https://www.forestry.gov.scot/publications/guidance-distinguishing-between-browsing-different-mammal-species).

If managing woodland with public access, carefully consider livestock grazing or visitor management to avoid any conflict between livestock and visitors, particularly those with dogs.

Additional information

Guidance for Sustainable Farming Incentive (SFI) participants on how to graze with livestock to maintain and improve habitats (https://defrafarming.blog.gov.uk/graze-with-livestock-to-maintain-and-improve-habitats/) from Defra.

Dogs in woodland: wildlife, livestock, and forestry operations (https://www.gov.uk/government/publications/managing-visitors-with-dogs-in-your-woodland/dogs-in-woodland-wildlife-livestock-and-forestry-operations) from the Forestry Commission.

Developing grazing plans for the conservation of semi-natural habitats (https://www.fas.scot/downloads/tn686-conservation-grazing-semi-natural-habitats/) from the Farm Advisory Service.

Breed selection

Associated species or groups of species: livestock and European bison (https://www.gov.uk/guidance/protecting-trees-from-mammal-damage-technical-guidance/livestock-and-european-bison)

When selecting domestic livestock for conservation grazing, consider the tendency of different species or breeds to browse) woody plants. The Breed Profiles Handbook (http://www.agrobiodiversity.net/topic_network/feral/Best_Practise/Cattle%20in%20conservation.pdf) details which cattle breeds are most and least likely to consume woody species as part of their diet.

Differences in browsing behaviour among breeds are largely anecdotal. The overall impact of livestock on treescapes is more likely to be influenced by factors such as:
- body size
- hunger
- availability of supplementary feed
Conservation grazing management should aim to avoid or minimise the need for supplementary feeding by selecting livestock whose nutritional requirements closely match the nutritional value of the available vegetation. Additionally, avoid grazing during winter when the nutritional value of most vegetation is at its lowest.

Additional information

The Breed Profiles Handbook: overview of different cattle breeds in conservation grazing (http://www.agrobiodiversity.net/topic_network/feral/Best_Practise/Cattle%20in%20conservation.pdf) from UK Grazing Animals Project.

Guidance sheet for domestic sheep (https://howtorewild.co.uk/guide/sheep/) from How to Rewild.

Guidance sheet for domestic cattle (https://howtorewild.co.uk/guide/cattle/) from How to Rewild.

Translocation

Associated species or groups of species: Eurasian beaver (https://www.gov.uk/guidance/protecting-trees-from-mammal-damage-technical-guidance/eurasian-beaver)

Translocation is the process of relocating living organisms from one area to another. For Eurasian beavers, this typically involves trapping the animals in the wild and releasing them into a different location.

The translocation of Eurasian beavers may be considered necessary in any of the following circumstances:

management translocation: when animals are relocated to mitigate negative impacts, such as human-wildlife conflicts

conservation translocation: when animals are relocated as part of a conservation effort, such as a managed reintroduction programme

welfare translocation: when sick, injured or orphaned animals are rescued and rehabilitated, and need to be released in a different location from where they were originally found

Due to their status as a European Protected Species in England, any translocation of Eurasian beavers requires a license from Natural England.

Additional information

Translocation guidance for Eurasian beavers in Scotland (https://www.nature.scot/professional-advice/protected-areas-and-species/protected-species/protected-species-z-guide/beaver/translocation-beavers-scotland) from NatureScot.

Advice and recommendations for Eurasian beaver reintroduction, management and licensing in England (https://publications.naturalengland.org.uk/publication/5010277084168192) from Natural England.

Conservation translocations: when you need a licence (https://www.gov.uk/government/publications/reintroductions-and-conservation-translocations-in-england-code-guidance-and-forms/conservation-translocations-when-you-need-a-wildlife-licence) from Natural England.

Diversionary feeding and nutrient supplementation

Associated species or groups of species:
- deer (https://www.gov.uk/guidance/protecting-trees-from-mammal-damage-technical-guidance/deer)
- livestock and European bison (https://www.gov.uk/guidance/protecting-trees-from-mammal-damage-technical-guidance/livestock-and-european-bison)
Diversionary feeding and nutrient supplementation involve providing alternative food sources to redirect feeding pressure away from areas where mammals might cause damage.

The effectiveness of these methods as a viable tree protection option remains inconclusive. According to NatureScot (https://bestpracticeguides.scot/crop-habitat/), research findings are mixed, some studies show a reduction in damage, while others report no change or even an increase in damage.

Supplementary feeding can be:
- costly
- labour-intensive
- prone to unintended consequences
For example, supplementary feeding might cause the animals to become dependent on the provided food or increase the risk of disease transmission at feeding sites due to higher densities. Excess nutrients from the feed, when excreted through faeces, can increase nitrogen levels in the soil and negatively impact plant diversity.

For these reasons, diversionary feeding and nutrient supplementation are generally most effective on a small scale and for short-term protection of particularly vulnerable or valuable trees.

Additional information

Guidance on the effectiveness and possible disadvantages of using diversionary feeding as a management method (https://bestpracticeguides.scot/crop-habitat/) from NatureScot.

Immunocontraception

Associated species or groups of species:
- Eurasian beaver (https://www.gov.uk/guidance/protecting-trees-from-mammal-damage-technical-guidance/eurasian-beaver)
- grey squirrel (https://www.gov.uk/guidance/protecting-trees-from-mammal-damage-technical-guidance/grey-squirrel)
- deer (https://www.gov.uk/guidance/protecting-trees-from-mammal-damage-technical-guidance/deer)
- horses and ponies (https://www.gov.uk/guidance/protecting-trees-from-mammal-damage-technical-guidance/horses-and-ponies)
Immunocontraception is an innovative method for managing animal populations by using the animal’s immune system to prevent reproduction. The approach typically involves administering a contraceptive vaccine that targets specific reproductive proteins or hormones, triggering an adaptive immune response resulting in temporary infertility.

The most commonly used immunocontraceptives developed for mammals, are those based on:
- gonadotropin-releasing hormones (GnRH)
- zona pellucida (ZP) proteins
While many laboratory and captive studies have tested the effects of immunocontraceptives on individual animals of several species, few studies have assessed their impact on wild populations. These methods are not yet widely available to land managers in the England, but scientific trials are ongoing, which may lead to broader applications in the future.

Additional information

Reducing grey squirrel overpopulation: The role of contraceptives in conservation (https://aphascience.blog.gov.uk/2024/09/30/reducing-grey-squirrel-overpopulation/) from the Animal and Plant Health Agency (APHA).

The potential role of contraception in the management of wild deer populations (https://bds.org.uk/wp-content/uploads/2021/01/Bullet-or-Needle_Deer-AUTUMN_2019.pdf) from the British Deer Society.

Mitigate flood risk (from Eurasian beaver activity)

Anti-burrowing barriers

Associated species or groups of species: Eurasian beaver (https://www.gov.uk/guidance/protecting-trees-from-mammal-damage-technical-guidance/eurasian-beaver)

Where burrowing into flood banks poses a flood risk to agricultural and woodland habitats, several anti-burrowing techniques have been trialled across Europe. These include:
- inserting interlocking sheet metal into the main flood bank structure
- inserting welded wire fabric into the main flood bank structure
- reinforcing riverbanks with large rocks or concrete
Attempts to use geo-textiles in the design of new flood walls has, so far, proven unsuccessful.

Although burrowing can generally be prevented by the installation of such barriers, these options may be neither commercially viable or ecologically desirable along extensive stretches of rivers and streams.

Additional information

Managing wild Eurasian beavers: A review of European management practices (https://www.nature.scot/sites/default/files/2017-07/Publication%202015%20-%20SNH%20Commissioned%20Report%20812%20-%20Managing%20wild%20Eurasian%20beavers%20a%20review%20of%20European%20management%20practices%20with%20consideration%20for%20Scottish%20application.pdf) from NatureScot.

Eurasian beavers in Scotland: Strategic environmental assessment (https://www.nature.scot/sites/default/files/2023-11/BEavers%20in%20Scotland%20SEA%20Environmentla%20Report%20-%20May%202017.pdf) from NatureScot.

Support and advice for landowners living alongside Eurasian beavers in England, Scotland, and Wales (https://beavermanagement.org/) from the Beaver Management Group.

Check if you need permission to do work on a river, flood defence or sea defence (https://www.gov.uk/permission-work-on-river-flood-sea-defence) from the Environment Agency.

Realignment of flood barriers

Associated species or groups of species: Eurasian beaver (https://www.gov.uk/guidance/protecting-trees-from-mammal-damage-technical-guidance/eurasian-beaver)

The majority of Eurasian beaver foraging activity occurs within 10 metres of the water’s edge. Creating 10 to 20 metre buffer strips of wet woodland (https://www.nature.scot/sites/default/files/2017-07/Publication%202015%20-%20SNH%20Commissioned%20Report%20812%20-%20Managing%20wild%20Eurasian%20beavers%20a%20review%20of%20European%20management%20practices%20with%20consideration%20for%20Scottish%20application.pdf) is suggested as a potentially effective approach to reduce damage of tree stock, although this method can be expensive.

Dam modification or removal

Associated species or groups of species: Eurasian beaver (https://www.gov.uk/guidance/protecting-trees-from-mammal-damage-technical-guidance/eurasian-beaver)

In extremely rare cases, Eurasian beavers’ dam building behaviour can cause commercial woodlands to flood. Pipes can be used as flow devices (https://howtorewild.co.uk/guide/beavers/) to bypass dams and thus reduce flood risk without disturbing the dam itself.

While dam-notching (the removal of a small section of the dam) or complete dam removal can reduce flooding in the short term, dams can be quickly repaired or replaced by Eurasian beavers, increasing the risk of them damaging additional trees.

In England, you must apply for a mitigation licence (A12) (https://www.gov.uk/government/publications/european-protected-species-apply-for-a-mitigation-licence) from Natural England to remove a Eurasian beaver dam that is associated with a lodge.