by Dave Goulson
With the benefit of hindsight, this whole saga seems spectacularly foolish, and the solution to the problem of overgrazing by elk self-evident – reintroduce the wolves. Of course some people suggested this, but it was not until the 1980s that the idea began to be taken seriously. Finally, after decades of argument, in 1995 fourteen Canadian wolves were introduced to large pens at Yellowstone, and after a few months of acclimatisation the gates were opened. The next year a further seventeen were added.
Despite occasional persecution from disgruntled hunters, the wolves thrived. Within just four years there were over a hundred, and the numbers have since fluctuated between eighty and 170. Some have spread beyond the park boundary, where they can legally be shot, but this is a pretty wild part of the world, and many survive – in total, there are thought to be perhaps 250 in the park and surrounding ranges, which may sound like a lot until you reflect upon the size of the area involved. Even if all of these wolves were in the park, it still only amounts to one per thirty-six square kilometres.
Despite this low density, the wolves seem to have had a huge effect on the Yellowstone ecosystem, far beyond simply reducing the elk numbers, which have dropped by about 50 per cent, effects that have been documented in detail by William Ripple, an ecologist from Oregon State University. He argues that the presence of wolves has not just reduced the number of elk but has profoundly changed the behaviour of those that remain. In particular, they tend to avoid steep-sided river valleys, where it is harder for them to see wolves approaching, and instead they stay out in the open. Elk love to browse aspen, cottonwood and willow, and willow grows in damp places along riverbanks. Without wolves the extent of woodland had declined considerably, which had impacted on beavers, which rely heavily on willows for their winter fodder. Beavers had all but disappeared from Yellowstone, but with the wolves back, the willows began to recover and the beavers with them. Beavers themselves are ecosystem engineers – their dams create more wetlands and marshes, encouraging yet more willow to grow, and also providing habitat for amphibians, wading birds, and so on. The diversity of aquatic habitats they create, from deep pools to fast riffles to shallow marshes, also encourage a range of insects and fish species. Their dams also help to store water, reducing bank erosion and flooding downstream during heavy rain – all in all, for a chubby brown rodent with outsized teeth they have a pretty impressive impact.
According to Ripple, the benefits of the wolf reintroduction were seen elsewhere too. Coyotes had thrived in the absence of wolves, but they were driven back to steeper ground where they could escape being depredated, which benefited populations of small mammals and ground-nesting birds that the coyotes had been eating. The remains of elk carcasses left by the wolves provided food for scavengers such as ravens, wolverines, bald eagles, even bears, the latter also benefiting from the revival of berry-bearing shrubs along the riverbanks. The ripples of effects radiating outward from the wolves are often described as a trophic cascade, and it makes a captivating story in which restoring the ecological balance has had profound benefits for wildlife across a huge area. The tale has been repeated often, in magazines, books and nature documentaries, and it has captured the hearts of many.
Some scientists have recently questioned whether the story is quite as neat as described by Bill Ripple. Some attempts to test his ideas have not supported them – for example excluding elk from riverbanks does not necessarily result in increased willow growth, and finding direct evidence that elk are more likely to be depredated if they visit the riverbanks has also proved difficult. Nonetheless, most agree that the wolves and then the beavers have had profound and positive impacts on Yellowstone.
After reading about Yellowstone, and travelling to Oostvaardersplassen to meet Frans and observe first hand what was happening there, Charlie decided to try something similar at Knepp. In 2004 he took more land out of conventional production, and in 2009 the bulk of the estate went into a ‘Higher Level Stewardship’ agreement by which he obtains fairly substantial subsidies from Natural England for supporting biodiversity. The land was entirely enclosed with tall deer fencing, unfortunately broken into three blocks because of the roads that run through the estate. Internal fences and gates were then removed, leaving only the old network of hedges. There were already roe deer on site, and to these were added old English longhorn cattle, Tamworth pigs, fallow deer and Exmoor ponies. Charlie would have dearly loved to introduce wild boar, a native species in the UK but hunted to extinction perhaps 700 years ago. Although it is legal to obtain and keep them, they have to be contained within boar-proof fencing which would have been prohibitively costly to erect around the whole estate, so the Tamworths were chosen as the nearest thing. As with the cattle and ponies, Tamworths are an ancient breed that can pretty much look after themselves – they are excellent mothers, and with much longer snouts than other domestic breeds so they are well suited to rooting about for natural food. They are also very resistant to sunburn – it wouldn’t be much of a rewilding project if Charlie and his team had to rush out and apply sunscreen to the pigs whenever the sun came out.
Ever since, the animals have been more or less left to look after themselves. The deer population has grown and they are now regularly culled to keep them in check. Likewise, surplus cattle are sent to slaughter, and their meat fetches a premium price in London markets. Otherwise, the animals are left in peace; they are outdoors all year, of course, fending for themselves, giving birth naturally and looking after their young as animals instinctively do. The vegetation is not managed in any way – the land is simply left to develop as it will, with no attempt to keep it clear of trees or to steer it in any way at all.
It was now about ten years on from when this grand experiment had started, and I was desperately excited to see what was actually happening out in the fields. Charlie led us outside to where he had a huge old vehicle parked, a six-wheeled ex-Austrian army open-topped troop carrier, capable of going more or less anywhere. We jumped in the back and off we roared. It felt as if we were off on a proper adventure, a feeling one doesn’t often get in Sussex.
What struck me first as we bumped and jolted across the estate was how variable the different fields were. Some were open grassland – yellow with buttercups, and dotted with cowpats and horse dung, though we didn’t initially see any large animals. Rabbits scampered away in front of us, and the remains of ones that had been eaten by buzzards – bits of fur and bones, the odd furry foot – were scattered on the grass. When we bounced through a gap in the hedge where once a gate had separated the fields, the next field had an entirely different character. Scrub had moved in – bramble and wild rose, the delicate flushed-pink blooms of the latter just beginning to open. Spiny shrubs – blackthorn and hawthorn – had also colonised, and together these four plant species formed dense defensive clumps, fortresses against the livestock, some of which had grown to be several metres across and a couple of metres tall. We stopped and climbed out for a closer look. Despite their thorns and spines the plants were clearly still grazed, with their outer leaves heavily nibbled and shoots bitten off. Nonetheless, they were clearly growing outwards, albeit slowly. Fascinatingly, from the centre of the larger clumps, just beyond the reach of the grazers, the delicate fronds of ash, oak and hazel were protruding. They could never have survived without the protective shield of the thorny shrubs around them. Clearly these fields were slowly turning to woodland, the thorny plants that are able to tolerate grazing ultimately bringing about their own demise, for they will eventually be shaded out by the trees growing through them, though it might take another fifty or one hundred years before anything like a closed canopy can form above them.
When I kicked over a drying cowpat – an antisocial behaviour that entomologists are prone to – I was struck by how many dung beetles and their larvae were burrowing within. A moment’s reflection explained why. These cows were not being regularly dosed up with Avermectins, worming drugs that are routinely given to livestock around the world and
render their dung toxic to insect life, in turn reducing the abundance of prey for swallows, starlings, and so on. These pats were au naturel, undoctored and hence a fabulous breeding ground for a host of creepy-crawlies – so far, twenty-four different species of dung beetle have been found at Knepp.
Evidence of rootling by the pigs was everywhere – great patches of earth, sometimes half an acre or so in extent, where the sods had been ripped up and scattered. I had seen this in the forests of France and Spain where wild boar abound, but never before in Britain. It looked messy, but in ecological terms this disturbance is a natural process, and probably an important one. The churning of the soil provides bare patches, hillocks and hollows, providing places for plants to germinate and warm, sheltered microclimates for bees and butterflies to bask in. We associate rare arable weeds such as cornflowers and corncockle with the disturbance created by arable farming, where they once thrived amongst the crops until modern herbicides and seed-cleaning methods eradicated them. One might wonder where they lived before the arrival of man – perhaps the answer is that they once depended on the action of wild boar to create patches of bare ground for them?
We jumped back in and clattered through a couple more similar fields, but then the next was completely different – a dense forest of sallow trees, already ten metres high, and packed together so closely that even on foot it was a struggle to squeeze between them. Why was this field so different? Charlie explained that in part it was down to the behaviour of the grazing animals, especially the cows. When first introduced, they had huddled together in the centre of the field, unable to comprehend their sudden freedom. All of their previous lives they had lived in enclosed fields, and they didn’t know what to do. It took them weeks to venture into the next field, and months before they had explored the whole estate. Some areas they seemed to avoid, though there were no wolves to frighten them off, and so these were ones that quickly developed into forest. Sallows have light, fluffy seeds that blow on the wind, so they can colonise very quickly. It also seemed that the exact year in which a field came into the scheme affected how it developed – Charlie suspected that it might just depend on whether it happened to be a good mast year for acorns, or ash seeds, or whatever. What was so refreshing about all of this was that it was natural, for nature was taking its course, doing its thing, with no human hand trying to interfere. With no goal in mind, Charlie doesn’t care what happens at Knepp, he just wants to see what will happen. It took me a while to get my head around this, for all of the conservation efforts I had been involved in before in my life were goal oriented – we wanted to reintroduce an extinct bee, or create 100 hectares of flower-rich habitat, or prevent the spread of an invasive species. Never had I come across the idea that one could just let go, stop trying to be in charge. It was really rather wonderful.
We pulled over by an elaborate, rustic tree platform some six metres in the air, built around a venerable old oak. Charlie shushed me, for I was gabbling noisily to Ted, and we climbed quietly up to the platform. I wasn’t quite sure why we were being quiet, but thought better than to ask. From the platform we were looking out over a large shallow expanse of water and marshland. It had once been an arable field, but they had scraped out the soil and banked it up to dam a small stream, doing work that beavers might perform if they were still present. In a similar way, Charlie and his team have also reinstated meanders in the River Adur that runs through the estate. His ancestors had canalised it, creating a deep, straight channel with the intention of draining water effectively from the land during winter floods. There is now good evidence that this just creates worse flooding downstream, but at the time it was well intentioned. It also removes much of the biodiversity. Just as the beavers have done at Yellowstone, restoring the bends creates areas of shallow water, deep water, fast sections and sluggish backwaters, in turn providing a diversity of niches for water plants, insects and fish.
We stood quietly in the tree platform, listening to first a cuckoo and then a turtle dove calling in the distance. Both are species that have undergone huge declines in recent years, but seem to be doing well at Knepp. A red kite cruised silently above us, lazily flicking its long forked tail to steer left and right as it quartered the ground in search of something to eat. Charlie pointed towards the scrub to our right and I noticed three red deer, two does and a calf, emerging from the shadows of a sallow copse to wade in the shallows, silently browsing on the tender leaves of semi-submerged willows. Their burnished russet hides glowed in the sunshine, their muscles shivering and their tails flicking to ward off flies. As we watched the deer suddenly froze, alert, their eyes and ears trained on the far bank of the lake where a Tamworth sow emerged from the undergrowth, trailing three piglets behind her. The deer relaxed as the four pigs noisily slurped at the muddy water. I was spellbound – it was almost as if we were on safari in East Africa, but the more remarkable because I was just thirty kilometres from home. On one level I knew these were just pigs and deer – everyday sights – but somehow because they were living wild the whole experience was entrancing.
As we watched, Charlie quietly told me a little more about the pigs. Apparently they sometimes submerge themselves entirely in the lakes, disappearing under water like miniature hippos as they truffle about in the mud of the lake bed in a hunt for swan mussels which they love to crunch up and slurp down whole like huge oysters.fn4 In winter they tend to sleep in piles to keep warm, and occasionally the one at the bottom gets asphyxiated and dies. These pigs are new to wild living, but on the whole they seem to have adapted astonishingly well. Watching the sow wallowing in the shallows with her piglets, I couldn’t help but be struck by the contrast between these pigs and those reared on factory farms that spend their lives in crates, unable to move more than a foot or two.
Later in the day we came upon a herd of longhorn cows, half a dozen of them with three calves in tow, wending their way along a network of trails worn between the clumps of bramble and blackthorn, browsing as they went. They have now clearly got over their agoraphobia, and seemed very content with their lot. English longhorns are a charming, scruffily irregular breed, their longish hair blotched blue-grey and white, the colours of an approaching storm, their huge horns curved wonkily. Although at Knepp they live their lives more or less entirely without the interference of man, they remain quite tame, allowing us to approach to within a pace or two. There are public footpaths through the estate, so choosing a placid breed was vital. Apparently breeds with long horns tend to be very gentle since, if they were not, they would be far too dangerous and would long-ago have been culled.
What is most remarkable is that these domestic breeds, maintained in captivity for many hundreds of generations, still retain instincts that can have been no use to them for millennia. Charlie explained how natural behaviours had somehow surfaced in the few years since the cattle were released. They naturally seem to form themselves into herds of a dozen or so, led by a dominant female – if a group becomes too big, it divides into two and they go their separate ways. When she is about to give birth, a cow will leave the herd and go into dense undergrowth in the woods. There she leaves the calf, returning to the herd for much of the day but popping back to suckle the calf at intervals. This might seem like a dubious strategy, for the new-born calf is more or less helpless and she is leaving it unprotected, but this is exactly what many wild animals such as deer naturally do. Perhaps in their evolutionary history, when wolves and other predators roamed the land, tucking the calf out of sight in the woods was a safer bet than having it out in the open, where it would be very obvious to a wolf pack which might then harry the protective herd away from the calf and thus have an easy meal. George Monbiot argues that humans retain ancestral memories or instincts from the time when we were hunter-gatherers, and perhaps these cattle have also inherited behaviours from their extinct aurochs ancestors. I found it reassuring that, even after so long in domestication, caged and with their free will removed, these animals still possess some of the
instincts of wild beasts.
Of course the obvious thing that is missing from Knepp is a top predator. In Yellowstone the restoration of wolves has been hugely beneficial, but the sad truth is that Knepp isn’t anywhere near big enough to support wolves, even if one could persuade the authorities and the local people that it would be a good idea. Some have mooted the idea of reintroducing wolves in remote parts of Scotland, and this seems plausible (and to my mind is a wonderful prospect), though there is huge opposition and it seems unlikely that it will ever happen. The ecological case is pretty sound – parts of the Highlands suffer from horrendous overgrazing by huge populations of red deer, just as used to be the case in Yellowstone. Wolves actually occur in most European countries, with populations in Spain, Italy, Sweden, Finland and most of Eastern Europe. Small numbers have moved in to France, Germany, even Denmark and the Netherlands in recent years, so is it really so unthinkable to have them in Britain? They pose almost no direct threat to man, despite the lurid headlines,fn5 though of course they would take livestock – but if farmers were compensated, is that such a big price to pay? Yellowstone has seen a surge in tourists coming to see the wolves, bringing in lots of money to the local area – it seems to me that this might provide far more income to rural communities in remote corners of Britain than they currently obtain from keeping sheep.
Regardless of these arguments, wolves are not practical at Knepp, and nor indeed are lynx, despite being smaller and solitary creatures. Charlie did some back-of-an-envelope calculations and estimated that Knepp could support a population of about half a lynx, such is the large range they need – not likely to form a self-sustaining population. Man has to act as the top predator by culling the large herbivores, and of course the number they choose to take will influence how Knepp develops, so nature will never be entirely self-willed here. Nonetheless, it feels an awful lot closer to natural than anywhere else I have been in the south of England.