As we welcome Spring, with some areas in February blessed with the hottest temperatures on record for this month, the sudden omnipresent sound of birdsong is surely something few of us have been able to ignore. And in the wilds of Knepp Castle Estate, near Horsham, a remarkable recovery has been taking place in the population of our best-loved musical bird. Come April it’ll be time to get out your recording equipment and head off in the twilight to catch the night-time love call of the nightingale.
Few birds have inspired as much poetry as the nightingale, which has fluttered onto paper for centuries out of the nibs of poets from Ovid to Milton to Keats. Yet this feathered musical miniature has been declining rapidly in number in the UK, with numbers down by 91 per cent in the last 40 years.
In 2001 the 3,500-acre Knepp Farm Estate began a pioneering, rewilding project and now, almost two decades later, it is witnessing remarkable recoveries in wildlife numbers. In Knepp’s 2018 surveys, 19 singing male nightingales were recorded, which can only mean there were females to match.
“Using grazing animals as the drivers of habitat creation, and with the restoration of dynamic, natural water courses, the project has seen extremely rare species like turtle doves, nightingales, peregrine falcons and purple emperor butterflies now breeding here, and populations of more common species are rocketing,” says ecologist Penny Green, with Knepp Wildland.
“The growing out of hedgerows and sallow scrub provides perfect nightingale nesting habitat and the abundance of insects, now there are no pesticides here, provide an important food source for both the adults and their young. The perfect time to hear these birds singing is in the dead of night, when all other birds are roosting, from the end of April to the end of May.”
Nightingales are known to fly some 3,000 miles away to West Africa for the winter, only to return by what is probably the same flight path to the same place their journey began – nesting within metres of their original nest, says Charlotte Owen, Wildcall Officer with the conservation charity Sussex Wildlife Trust.
“Only the males sing and they usually arrive here in mid to late April, a few days ahead of migrating females,” she said. “This gives them a head start in the race to find and claim a prime nesting site.” (Presumably to check out the local schools, and if there’s a good pub nearby.)
“Each male has an impressive repertoire of around 200 songs and will select different sequences and melodies depending on the time of day and the message he wishes to convey. They will often sing quite relentlessly, and since the females migrate at night the males must continue singing long after dark to advertise their presence and attract a mate.”
Studies have shown, she says, that males with a more ordered singing style and complex repertoire tend to feed the chicks more often – and are more likely to attract a mate.
Tracking a 3,000-mile flight path
The British Trust for Ornithology is an independent, impartial research organisation based in Thetford, Norfolk. It has 100 full-time staff and 60,000 volunteers who collect data to help its scientists monitor Britain’s birds. It also has 19,000 members, whose subscriptions help fund the work it does.
In 2009, 20 nightingales were caught and had tiny, one-gram devices attached to them. These geolocators tracked the birds’ flights, and a year later one of them was re-caught and information from the geolocator downloaded.
It had recorded the bird’s flight from southeast England, through Spain and Portugal then down the west coast of Africa to Senegal and Gambia. The bird did stop along the way, sometimes for several days, but at the moment that’s as detailed as the information can be.
The device failed on the return journey, but if we assume the bird returns along a similar route, we can calculate that it travels around 6,000 miles in a round trip.
Unfortunately the geolocators had failed on six other birds that were re-caught.
Back at Knepp, ornithologists will be waiting keenly to see how many nightingales nest on the estate for 2019, but in the meantime, there’s another success story.
There has been a 93% decline in the UK in turtle doves in just over 20 years, says Penny Green. But increasing numbers are coming back to Knepp, with 18 singing males recorded last year.
“They have very specific needs when nesting, including thickets or sallow trees to nest in, a sparse or bare tree to sing from, water near to the nest site, and lots of annual weeds so they can eat the seeds,” she says.
“A perfect storm has meant that all of these important criteria have been met at Knepp, and now we are blessed to be able to hear several singing males on a walk in the Knepp wildland. May and June are great months to listen out for it, with first light and late afternoon the prime times.”
So what are you waiting for? Grab your binoculars, maybe a torch, and go and find out for yourselves.