Nightingales are one of the most remarkable and surprising successes of the rewilding project. In 2018 the British Trust for Ornithology (BTO) recorded a 92% 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 seven nightingale territories at Knepp. But in 2012 (post-rewilding) a survey conducted by a Masters student at Imperial College London identified 34 territories, 79% of which were thought to be paired birds that were potentially breeding.
The Imperial College study 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.
Nightingale territories are usually found in habitats associated with woodland and woodland edge, with coppiced woodland being particularly important historically. Their dramatic decline is thought to be in response to changes in woodland management and intense deer pressure, resulting in the loss of low, dense under-storey vegetation. Surveys over the last 30 years, however, have identified scrub – such as in the Southern Block at Knepp – as being particularly important habitat for nightingales, providing suitable habitat structure for up to twice as long as coppiced woodland. The fact that scrub is rarely tolerated in the modern landscape has no doubt contributed significantly to the nightingale’s decline.
But it also demonstrates how we can be deceived by our own observations and received wisdom. 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.
In 2021, 40 singing males were identified, singing from Knepp’s billowing hedgerows and patches of scrub. In addition to these males, and their mates and offspring, many other nightingales utilise the Knepp scrub in passing as they feed up for their autumn migration.