Nightingales are one of the most remarkable and surprising successes of the rewilding project. In 2010 the British Trust for Ornithology (BTO) recorded a 90% decline in the UK nightingale population since 1970. Once widespread in Britain, their intoxicating song the inspiration for Shakespeare, Spencer and Keats, their range is now limited to the south-east corner of England and numbers of this lovely African migrant continue in free-fall.
Prior to the rewilding project, in 1999, a national nightingale survey by the BTO recorded only 9 nightingale territories at Knepp. But in 2012 (post-rewilding) the survey identified 34 territories, 79% of which were paired birds that were potentially breeding. In 2013, that number had risen to 42 pairs in the Southern Block alone.
Studies conducted by Imperial College London have homed in on the habitat nightingales are choosing at Knepp - overgrown hedges 8-14 metres deep, made up of mixed shrub species with a preponderance of blackthorn. The cathedral-like interior of these thorny fastnesses provides the adults and their fledgling chicks with a safe place to forage for insects in the leaf-litter.
Previously in the UK, nightingales had been considered essentially a woodland species. Their dramatic decline was thought to be due to changes in woodland management. But Knepp shows clearly that nightingales thrive in thorny scrub. The fact that scrub is no longer tolerated in our landscape has no doubt accelerated the nightingale's decline.
But it also demonstrates how we can be deceived by our own perceived knowledge. We think we know the preferences of a certain species but forget that in our depleted landscape we may be observing it at the very limit of its abilities - not where it wants to be at all, but where it is clinging on for dear life. The potential of process-led projects like Knepp, where nature is allowed to reveal herself rather than be dictated to by human management, is enormous. It allows us to observe what species like nightingales really want and that, in turn, will help us to plan for their conservation in the future.