A major twenty-year ecological review at Knepp Wildland Foundation has revealed one of the most dramatic wildlife recoveries recorded in the UK, offering compelling evidence that rewilding can restore biodiversity at remarkable speed and scale.
The review, published in January 2026, documents extraordinary increases in birdlife, butterflies, dragonflies and other species across the 3,500-acre Sussex estate. Since the beginning of the project, breeding bird abundance has risen by an astonishing 916%, while species richness has increased by 132%. Nightingales — one of Britain’s most threatened songbirds — have risen from just nine singing males in 1999 to sixty-two in 2025, making Knepp one of the species’ most important strongholds in the country.
The figures represent a remarkable transformation for land that was once intensively farmed and economically struggling. As recounted in Wilding by Isabella Tree, Knepp had long battled against the realities of poor clay soil and industrial agriculture. Rather than continuing an unprofitable farming model, Tree and her husband, Charlie Burrell, chose a radically different path: allowing natural processes to shape the landscape once again.
Instead of carefully controlling the land, fences were removed, drainage systems dismantled, and rivers allowed to reclaim their natural courses. Dead trees were left standing, scrub regenerated naturally, and free-roaming grazing animals were introduced to mimic the ecological functions once performed by extinct wild herbivores. Old English longhorn cattle, Exmoor ponies, Tamworth pigs, red deer and fallow deer now move freely through the estate, creating an ever-changing patchwork of woodland, thorny scrub, grassland, ponds and open glades.
This dynamic mosaic of habitats has proved extraordinarily effective for wildlife recovery. Species that had disappeared or become increasingly rare across much of Britain have returned in significant numbers. Turtle doves, whose UK population has collapsed in recent decades, increased by 600% at Knepp, with twenty-three singing males recorded in 2020. Purple emperor butterflies have also flourished; in 2025, observers counted 283 individuals in a single day, placing Knepp among the most important sites for the species in Britain.
Butterfly diversity overall has more than doubled in some areas since 2005. Dragonflies and damselflies have shown similarly dramatic recoveries, with abundance increasing by 871% along the restored River Adur corridor. Entomological surveys also recorded substantial gains in rare invertebrates and species of conservation concern, illustrating the wider ecological impact of habitat regeneration.
The success of Knepp has become internationally influential in the broader rewilding movement. Unlike traditional conservation models that often rely on maintaining fixed habitats through intensive management, Knepp demonstrates the ecological richness that can emerge when landscapes are allowed to evolve naturally through disturbance, grazing, flooding and regeneration. Scrub — long dismissed in British conservation as untidy or unproductive — has emerged as one of the estate’s most valuable habitats, especially for birds such as nightingales and turtle doves.
The project has also contributed to changing public and political conversations about land use in Britain. Rewilding, once regarded as fringe or impractical, is increasingly discussed as a potential response to biodiversity collapse, soil degradation and climate pressures. Knepp is frequently cited as one of the clearest examples of how ecological restoration can coexist with economic sustainability through nature tourism, safaris, camping, organic meat production and education programmes.
Speaking about the findings, Isabella Tree described the estate’s transformation as a shift “from a depleted, polluted, dysfunctional farmland to one of the most significant biodiversity hotspots in the UK.” She argued that the scale of recovery demonstrates how much life landscapes can support when natural processes are restored.
Ecologist Fleur Dobner, who worked on the review, highlighted the importance of habitat diversity created through rewilding. What had once been monoculture farmland, she explained, has become “a rich mosaic of parkland, scrub, hedgerows, glades and grassland,” with biodiversity continuing to rise year after year.
The Knepp review arrives at a critical moment for British conservation policy. The UK has committed to protecting and restoring 30% of land for nature by 2030, yet progress has been widely criticised as too slow. For advocates of rewilding, Knepp offers powerful evidence that large-scale ecological recovery is not only possible, but can happen far more rapidly than many scientists once believed.
What makes Knepp especially significant is not simply the return of individual species, but the restoration of ecological relationships and processes. Rather than recreating a static version of the past, the estate has become a living experiment in how nature can regenerate when given space, time and autonomy. After two decades, the results suggest that rewilding may be one of the most effective tools available for reversing biodiversity loss in Britain.
