How to Rewild



Animal Guide


Sheep are perhaps the easiest livestock to keep, with few movement restrictions, and some breeds requiring little care. But they’re also misunderstood by many conservationists and rewilders – these animals, while not native to Britain, can be helpful in the management of some British ecosystems.

Our livestock guides are intended to help you understand how the animal can be used in the context of nature recovery projects, and how they may benefit from wilder ecosystems and alternative land management.

These guides are not a single source of information for livestock care or handling, as this topic is the subject of entire books. For sheep on smallholdings, the Haynes Sheep Manual is recommended.

Impact on Nature

There’s a lot of misinformation about sheep in ecology and rewilding. This section is based on real world case studies and long-term, peer-reviewed field research:

More flower diversity, but trees are killed off.

If they’re introduced into closed canopy woodland with dense underwood, sheep can increase the diversity of ground flora. But they also eat any young trees, and increase grass cover. These animals are strong enough to crush bracken and tall vegetation, but not scrub or small trees, so at first, their impact on woodlands tends to be limited to ground level.

Over time however, the way that sheep eat young trees (‘preventing recruitment’) creates a more open canopy and will eventually turn the woodland back to grassland. Removal of sheep grazing from an Oak woodland edge allows natural succession to occur, expanding the size of the forested zone; in contrast, a woodland edge will recede if sheep are present. Sheep frequently get through fences into woodland, and even low levels of activity can have long term negative impacts on woodland health.


At high densities, sheep can prevent the growth of new scrub by tightly grazing grassland. Most sheep will preferentially eat grass rather than scrub, but some breeds are exceptions to this rule.

The British Primitive will preferentially browse on scrub, helping to control its spread, while Soay Sheep will eat Bramble. Medium to high densities of these breeds (1-3/ha) will create a scrub-free grassland ecosystem, rather than a mosaic habitat. 

However, most breeds of sheep will only consume small amounts of scrub – not enough to reduce its extent. At moderate to low densities, grazing of sheep will not prevent the encroachment of scrub, especially over longer time periods.


Bracken is toxic and distasteful to sheep, and they are likely to avoid eating it if better grazing is available. However, when grazing intensity is reduced, it appears that Bracken coverage seems to increase, so these livestock must be having some controlling effect. Some sheep breeds are particularly good at controlling Bracken; Soay Sheep bite off the young shoots (without consuming them), so they are an effective control system for this invasive plant.


The best evidence we can find for the impact of sheep on Heathland comes from exclusion experiments, where areas are fenced off to prevent grazing. Surprisingly, two studies in the uplands of Britain, both of which lasted over a decade, found that removing of sheep did not result in woodland succession. Instead, heather grew taller and grasses became less dominant.

These ecosystems likely had a very degraded seedbank in the soil, owing to the constant grazing pressure. That means there were few tree seeds available to recolonise the habitat when sheep were removed. The authors of one study noted that manual intervention (tree planting) would probably be required to create woodland within the first ~50 years after sheep removal.

Beyond the recommendations for restoring Heathland, this also suggests that sheep grazing on heathland reduces the diversity and abundance of trees over time.


Some grassland plants are named after sheep due to their close relationship; Sheep’s Sorrel, Sheep’s Fescue, Sheep’s Bit. And sheep are often used to maintain low nutrient Acid, Neutral and Calcareous Grassland habitats. Their stocking density affects the sward height (grass depth), which in turn determines which plant and invertebrate species are present. 

Sheep have a positive impact on the biomass of fungi – especially species like waxcaps, which are dependent on short, grazed turf. However, overgrazing can reduce wildflower biodiversity – it’s worth experimenting to find the right stocking density when using sheep to maintain biodiverse grassland ecosystems.

In recent history, transhumance was common, where sheep were grazed on uplands in the summer, put on weight, before moving back down to the lowlands over winter. An alternative system involved ‘folding’ – keeping sheep on upland during the day and in a sheepfold overnight. These systems shifted the nutrients away from uplands, maintaining their low nutrient soils. Now, grazing practices have changed and this is no longer common in Britain. As a result (and also due to increases in atmospheric nitrogen deposition), our upland grasslands have become nutrient-enriched, and lost some of their plant diversity. It’s not just the sheep that are important, but how the animals graze.

Sand Dunes

Sand dunes naturally form a patchwork of high and low plant diversity zones, known as hollows and hummocks. Sheep grazing can flatten out this variety and creates a more uniform pattern of plant diversity with less woody species. However, higher density sheep grazing also prevents scrub encroachment, maintaining a more open habitat. This promotes the establishment of a diverse community of ground flora, improving overall biodiversity. Rabbits and sheep have similar impacts on dune ecosystems, so one can be used to replace many of the functions of the other. Overgrazing can occur when high densities of both rabbits and sheep are present.

Salt Marsh

Salt marsh grazing is a traditional practice, which has almost disappeared from modern landscapes. However, moderate grazing pressure increases the diversity of plant species in a salt marsh ecosystem, mainly in higher areas of the habitat where it is less often flooded by the sea. But overgrazing can have a negative impact (especially in lower areas), so getting the stocking density right is a balancing act. 1-5 sheep per hectare in high salt marsh appears to be appropriate to maintain a healthy habitat.

Soay lamb
Soay Sheep grazing on clifftop calcareous grassland - this heritage breed are suitable for harsh conditions.
Salt Marsh grazed by sheep
Grazed upper salt marsh habitat in Normandy, France - a traditional practice which is now less common in Britain

Premium Meat Production

As with pigs, the highest quality meat comes from sheep which have been kept lean for a long time, then allowed to fatten up rapidly towards their end of life. But other factors which are extremely important are the livestock’s roaming behaviour (long distances = higher quality) and the diversity of forage they are provided with (higher diversity = higher quality).

Mutton from cull ewes, which is typically tough and low value, can be transformed into premium quality, world class meat by providing a diverse ecosystem and encouraging the animals to move regularly through it. These sheep can be acquired cheaply, as they are traditionally sold for slaughter, and then grazed in an agroforestry system for a year, before the meat is sold at a profit.

Any premium meat product where the price comes from its quality rather than a label (organic etc), is heavily dependent on the local market and supply chains. Establishing a relationship with restaurants and butchers can allow you to sell on high quality meat at a profit. But without these relationships, you may struggle to find a buyer for your product, regardless of its quality.

Common Osier
Osier is a quick-growing non-native Willow which has been grown in Britain as animal fodder since Roman times.

Tree Hay

While farmers have traditionally been told that sheep are happiest in grassland, many sheep will be only too delighted to eat trees and scrub. Not only will this improve their meat quality and mood, but also their health, due to the presence of minerals and nutrients in the tree bark and leaves.

There is very little scientific research in this area, with most of the useful information coming directly from farmers. But some peer-reviewed papers do exist – a willow extract was found to reduce gut and lung parasite load in sheep and goats. Feeding sheep on live willow increased their reproductive rate due to an increase in oestrus activity and conception rate. Willow fodder has had mixed results with weight gain, varying between positive and negative effects depending on the trial.

Farmers know that it doesn’t take a scientific study to work out whether something is good or bad for your livestock. As a peer-reviewed study on tree hay says; “farmers were surely able to recognize the forage quality of different woody species without any analytical methods, but according to milk yield or live weight gain of their livestock”.

That said, their data on the nutritional value of different tree species could be valuable. According to this paper, Oak, Beech and Hornbeam have lowest quality forage, while Hazel and Poplar/Aspen are more nutritious, then Elm, Ash, Lime and Sycamore* are highest in nutritional value.

From speaking to farmers, we’ve found that Silver Birch, Willow, Hazel and Alder are preferred by sheep. Alder is typically eaten late in the year. Other trees that the livestock may eat include Elder, Spindle, Downy Birch and Elm.

Willow is the easiest tree fodder to start with as it grows quickly and is easy to harvest – farmers recommend using pollarded trees. Pollarding means cutting above the browsing height of livestock, as opposed to coppicing, which is cutting at ground level. This avoids the tree hay being eaten while it is still growing.

The finger-width branches are cut in August, and dried by hanging in a dark place, like from the rafters of a barn. They may also be dried in piles on the ground, but tend to become infested with rats. These branches are then offered to the sheep throughout winter as ‘tree hay’. Feeding live branches is also possible, but bird nesting season may pose an issue due to disturbance when branches are green.

Providing tree hay on a larger scale – by felling whole trees or cutting large branches – can be an easier method of harvesting, though it’s less sustainable than pollarding. The trunks can be left on the ground over winter, and the bark will be stripped as the weather gets colder. Then lambs will use this refuge as cover, which can improve their confidence and health after birth. The debarked willow can then be used for firewood, though it does tend to pop and crackle.

Tree hay is a popular food, and sheep will readily approach the farmer as they carry in fresh branches every day or so. This provides an excellent opportunity for you to inspect and familiarise yourself with the flock, allowing health issues to be identified early. Sheep are reportedly also less likely to escape the field, as there is more of interest to them on the ground.

Farmers report that provision of tree hay reduces the need for worming treatments, protects them from liver fluke, reduces incidence of mucky back ends, and improves the mood of sheep so much that it can pull quarantined animals out of terminal decline.

*Sycamore is non-native, invasive and toxic to horses


Sheep pasture
Pollarded and coppiced willow growing within an old Somerset sheep pasture.

Wilder Fields

Adding trees to a sheep farm can improve the health and breeding success of sheep. While some farmers recommend grazing sheep in woodland, the long term impact of this will be loss of all the trees, as any young saplings will be eaten and older trees will slowly die off. 

However, it is possible to plant trees (especially pollarded willow) within sheep pasture, and use alley cropping systems to create more shade, wind protection and forage for the animals. Indeed, sheep have traditionally been used to graze orchards, and this system creates a vertical stack of productivity, keeping down tree pests and providing valuable shade for the animals in summer. Even scrub can be forage for sheep, as they will eat Hawthorn, and some breeds will readily eat Bramble, too.

Farmers may be concerned about letting their sheep into areas where toxic plants are present, but the animals tend to avoid species which are risky to their health. Interestingly, after his flock ate a half acre stand of Hemlock, Devonshire farmer Matt Chatfield reported no ill effects. In fact, he said, ‘mine were the only sheep in the area without liver fluke’. He believed that their constant low level exposure to natural toxins kept parasites at bay, and there is some evidence to support that plants (e.g. Chicory, Birds Foot Trefoil) can do this.

While trees can provide forage, they may also be able to reduce pests, too. Two farming sources claim that silvopasture (trees grown in pasture) and/or Scots Pine in particular are good for keeping flies away. There is nothing in the scientific literature that appears to either support or reject this claim.


Sheep Tips

If you’re working on a small scale, here are a few thoughts that could help you understand the potential and challenges of bringing sheep into a nature recovery project:

  • Sheep are notorious for escaping, so hedges are not enough – boundary fences will need to be installed and maintained.
  • When managing sheep across very large areas, NoFence collars may be more economical than fencing. However, they are not 100% perfect, especially in winter when units may need recharging.
  • NoFence is not effective in small or narrow projects, as a 15m boundary is required.
  • Soay sheep typically shed their fleece naturally, and are very low maintenance, requiring only a shelter for rain protection, so they may be ideal for low input projects.
  • Sheep don’t usually suffer from the effects of TB, but are affected by liver fluke and conditions like foot rot and foot scald. These are most common on wet land with access to ponds.

Further Information

Rare Breeds Survival Trust

Valuable information about conservation grazing and which breeds are suitable for different conditions.

Agroforestry Research Trust

Provides resources and training in the creation of wooded farm landscapes with high value for livestock.

Soil Association Agroforestry Handbook

Detailed guide to implementing agroforestry on a profitable working farm, with information about different livestock and tree species.