Rewilding Britain- Exploring the wild at Knepp

Since I first read 'Wilding: The return of nature to a British farm' by Isabella Tree, I have wanted to visit Knepp Estate. Knepp estate in Sussex, UK, is a 3500 acre former working farm, and is now a conservation project using large herbivore species to restore nature and increase biodiversity. The book offers a fascinating insight to the conservation project from its very beginning to the successes they are now seeing as the project continues. I discovered the concept of rewilding when I was first researching for an undergraduate essay on landscape-level conservation. For me, the idea that conservation wasn't just about saving one species at a time was pretty powerful. (As a foreword though, these ideas are new, controversial and this blog post only scratches the surface of rewilding)!

Rewilding doesn't seem to have a set definition, perhaps because it's value is in experimentation. But at it's core, it is a landscape-level conservation technique that aims to increase biodiversity by introducing lost species to create sustainable environments that sustain and manage themselves. It's an exciting idea that aims to make areas more 'natural' and reverse the effect of human disturbance. It's basis is in introducing large herbivores and other species that are 'ecosystem engineers' (species that have a large impact on shaping their environments).

I guess I'm not too late to the party, in that rewilding is a relatively new and contemporary approach to conservation. In the early 2000s, a couple of scientific papers (Sergey Zimov in 2005 and Donlan et al. in 2006) were published which discussed how as recently as 10,000 years ago (a tiny amount of time in the history of the earth), large areas of the planet were covered in grassland and maintained by large herbivores (think mammoths). From school biology/geography, we are taught (at least in the UK, I can't speak for the rest of the world), that all landscapes, if left long enough, will reach a state of dense forest known as it's 'climax' community. But these papers suggested that when we think about climax communities, we aren't considering the wildlife that lived there and how they would have influenced the landscape. It's a radical, yet perhaps obvious, idea, that wildlife is just as important in determining the plant community as the traditional factors we're taught about, like temperature, humidity and pH. Consequently, if you think about large herbivores grazing the landscape, the 'climax' plant community may be grassland and all its accompanying micro-habitats (in some biomes/landscapes) and not forest like we thought.

As a result of this idea, it may be that where there are dense forests (like Białowieża Forest in Poland- post coming soon!), they might not be the 'last remaining primeval forests', but instead a consequence of the gradual loss of large herbivores, whether through climate change or, more recently suggested, over-hunting by humans (another disputed idea). So what we think is the 'historical state' of a certain area is not perhaps true. New techniques, such as carbon dating and the pollen record, looking for the small particles that make up grasses (through looking at cores of rock and sediment where material has built up for millions of years) as well as looking at the teeth of fossilised animals, is beginning to suggest that smaller plants (such as grasses) were more prevalent than large woody trees than first thought. The absence of grass pollen in the pollen record may be because this type is much more fragile and less likely to remain in sediment, and not because it was absent in the landscape. So whilst the pollen record shows evidence of trees in the landscape, it cannot tell us the actual composition of trees to smaller grassland plants.

These ideas (of which I have given a very, very brief summary of the incredibly complex web of evidence and theories) are fundamental to the idea of rewilding, and creating the wood-grassland landscape that is considered the 'natural state' of the UK. The fantastic book 'Rewilding: The Radical new science of ecological recovery' by Paul Jepson and Cain Blythe is a fantastic and accessible read for anyone interested in learning more. Across the world there are a few examples of rewilding projects, but to avoid a further rabbit hole of information in this post, I want to focus on my trip to Knepp.

Introducing species

I've always been a big fan of visiting nature reserves and going for walks outdoors, but Knepp offers something a bit different. The introduction of an optimum number of several large herbivore species to graze and disturb the landscape creates a rich mosaic of habitats. The idea of introducing these species is to develop a fully functional ecosystem with as much freedom and little management as possible. There are relatively few places in the UK where there are free-roaming herbivores, and nowhere else where the land is being allowed to go 'wild'. The obvious missing factor in the environment are large predators such as wolves (which would have historically controlled these herbivore species), but the UK is densely populated so UK law, space and public opinion present a large barrier to introducing predator species. Instead, numbers of herbivores are human-controlled and the estate sells free-range meat, limiting numbers and providing necessary income for the project.

The herbivores that have been released include longhorn cattle, Exmoor ponies, Tamworth pigs and three species of deer; red deer, fallow deer and roe deer. The longhorn cattle were the first species we saw as we entered Knepp, grazing relatively close to the footpath. Whilst seeing domestic cows is a common sight in Britain, there was something special about knowing these animals are the most 'wild' they could be, with the freedom to roam in this environment relatively undisturbed. The species was introduced as a proxy for the auroch, a large wild cattle species that went extinct in the early 17th century and historically grazed across Europe. Introducing cattle is very important for the rewilding concept, they feed on both grass and other vegetation which slows tree growth in some areas and maintains the open habitat. Cattle also transport the seeds of more plant species than any of the other introduced herbivore species through their dung, caught in their fur or carried in their hooves. The longhorn cattle in particular is long-lived, hardy and a strong breeder which is important to both maintain and survive the self-sustaining, naturalistic environment of Knepp.

Tamworth pigs were introduced in place of wild boar, a species covered by the Dangerous Wild Animals Act of 1976; meaning it would be illegal to introduce them to Knepp. Wild boar are native to the UK and there is still a population of an estimated 4000 across the UK. Their presence is highly controversial, they are sometimes aggressive particularly when guarding their young, and can be threatened by dogs and dog walkers where there is contact. They also cause significant damage to farmland and managed gardens. Despite this, wild boar, and their proxy the Tamworth pigs, help to change the landscape to facilitate other species, particularly invertebrates and plants, making them a fantastic ecosystem engineer and conservation tool. Pigs create habitat disturbance by 'rooting', or digging/snuffling in the soil and ground. Doing this exposes the bare soil which encourages new plant growth, in turn attracting many species of birds and invertebrates, including rare butterflies like the purple emperor. Large clumps of soil kicked up by pigs creates anthills which provides food for bird species.

Unfortunately for me (as a huge horse lover), we didn't manage to see the Exmoor ponies at Knepp. They are an ancient breed, and a relatively close descendant of the tarpan, the equine species which existed in a pre-human Britain'. At Knepp there are two herds with a total of 28 ponies, perfectly designed to live 'wild' and withstand weather extremes with little human management. The ponies stimulate more complex vegetation structure and therefore encourage biodiversity by grazing on tougher parts of the grass and vegetation, therefore leaving the softer and shorter grass for the cattle to feed on. From what I've read, the interaction between cattle and equine species in grasslands is very interesting and only beginning to be understood. Regardless, they work well together to encourage the biodiversity that Knepp aimed to achieve.

The three deer species at Knepp all play slightly different roles in the environment. We were lucky enough to see the magnificent (although a little scary) display of several large red deer stags roaring and rutting for females. Red deer are native to Britain but found almost exclusively in Scotland. As such a large species, they have a large impact on vegetation, grazing grass when available but feeding on both higher and lower vegetation too. In winter, they de-bark trees to feed, creating a micro-array of habitats that we wouldn't even think to consider. Roe deer and fallow deer, whilst a similar size, also play different roles in the environment. Fallow deer are what you expect to see at deer parks, for example Knole Park in Kent, Richmond Park in London and Tatton Park in Cheshire. Parks like this were historically stocked with fallow deer to allow sport hunting by aristocrats. Fallow deer graze on grass as well as browse vegetation, so like red deer, maintain habitats at a variety of levels. Roe deer, of which there is only a small population at Knepp, exclusively browse vegatation and do not eat grass. They are also relatively shy and keep within the forested areas, feeding on saplings, bramble and other small plants.

The result

To avoid simply listing the wildlife successes that have been achieved at Knepp, you can visit the website to read about the amazing biodiversity that has been attracted by the landscape changes made by the introduced herbivores. Incredibly rare and endangered species from fungi, through plants, invertebrates, up to birds and mammals have now established themselves on the site. It has truly shown that returning the land to 'nature' could have a genuinely powerful positive impact on UK species abundance, and could actually help to reverse declines in some species. These species have colonised and appeared without human intervention, searching out and finding the brilliant range of undisturbed habitats within the estate. The project states clearly that they wish to let nature find it's own way to Knepp, with the exception of some species- beavers, bison and white storks- that are highly valuable to the ecosystem and would further encourage landscape change and biodiversity. Whilst beavers and bison have not yet been introduced to Knepp (although the project has hope for the future), white storks have and what a beautiful addition to the landscape.

When visiting Knepp we were lucky enough to see at least six individuals flying above us. I was also lucky enough to see storks in Poland when I visited in 2018, but to see them in the UK was incredible. White storks are a migratory species, wintering in areas of mainland Europe, Africa and India but historically native to Britain. Before recent reintroduction into the UK, the stork was extinct in Britain caused by persecution (as a symbol of Christianity and rebirth), habitat loss and hunting. Annually, around 20-30 individuals are seen in the UK, but the last record of breeding was in the 15th century. Yet in May 2020, a pair of storks at Knepp successfully bred and hatched their first chicks. From that moment onwards, the stork population at Knepp has grown with 19 juveniles released onto the estate that had been reared at Cotswold Wildlife Park. With many of the juveniles fitted with GPS tags, the project was able to see that many migrated away from England and safely found overwinting sites across Europe and Africa. Migrating adults have been returning to Knepp since January 2021, and there are many reports of displaying behaviours, bonding and nest buildings. Any juveniles that migrated in 2019 and 2020 will hopefully return to Knepp once they are around 3-4 years old and begin breeding themselves. The progress of the storks can be followed on the White Stork Project website or their Instagram page.

What was glaringly obvious to me as I read the book, and as I wandered around Knepp, was that every introduced species has such a valuable role to play in the 'rewilding' concept. As well as that, there is such a complex web of interactions between and within all the introduced species and all the biodiversity it has attracted. It is truly a living conservation project that you get to see with your own eyes and if you get the opportunity to visit then I would highly recommend it. It also gave me a newfound awe for British wildlife and British natural history. As a Zoo Conservation graduate, I thought my passion lay firmly with exotic animals outside of the UK, yet the whole concept of rewilding has shown me that British wildlife can be just as fascinating. More than this, it has shown me that conservation techniques are constantly adapting in the face of new historical evidence, and we can only hope to have success if we continue finding new ways to encourage biodiversity through letting nature take its own course.