Swallows dart above the reed beds while a little egret hunts among the bluey-green marshland grass and a pair of curlews circle, long, curving bills clearly visible, before heading out to sea. It is so quiet that you can hear the crackling sound that mud shrimps make as they feed in their burrows.
For centuries, this parcel of land on the Gower Peninsula in south-west Wales, Cwm Ivy, was an ordinary dot of sheep-grazed seaside pastureland. Then the stormy winter of 2013-14 hit, causing the sea wall to be breached and letting salt water pour in.
Rather than rebuilding the defences, the National Trust, which owns the land, let nature take its course and seven years on Cwm Ivy has turned into a pristine salt marsh, rich in flora and fauna.
Alan Kearsley-Evans, the trust’s general manager for Gower and Brecon, said Cwm Ivy was an example of what could happen if humans took a step back. “At almost every other site we are thinking: what do we have to do next? Here all we do is maintain fences to keep the sheep back but apart from that, we sit back and let it happen.”
Rising sea levels and extreme weather mean that difficult choices have to be made about how to defend, or not defend, areas of coastline. Kearsley-Evans said if the sea wall had been breached in a more populous area such as Llanelli across the estuary, it would need to have been rebuilt to protect homes.
But at the more remote Cwm Ivy, allowing the water in fitted with the trust’s shifting shores policy, under which it does not simply attempt to stop change such as coastal erosion but adapts with it. “We tried to back off here, to give nature space,” said Kearsley-Evans.
The winter of 2013 was a time of relentless rain as Atlantic storms battered the west of Britain. Villages in the Somerset Levels were cut off for weeks and part of a railway line in Devon was washed away.
At Cwm Ivy, a stream turned into a torrent and created a hole in the sea defences that had kept the land drained for hundreds of years. Residents were upset at first when the National Trust explained that it was not going to fix the wall. The salt water killed off the pastureland, turning it into mud. The stately Corsican pines and willow trees died. “It wasn’t pretty at first,” said Kearsley-Evans.
But the tides immediately began to bring in marshland and wildflower seeds. Otters were spotted, tempted back because once the sheep had been removed, there was cover for them.
A young osprey, the spectacular fish-eating bird of prey, stopped off for an autumn break at Cwm Ivy while in transit from north Wales to Africa. “That helped,” said Kearsley-Evans. “People began to understand what we were trying to do.”
The ranger Corrinne Benbow said one of her favourite creatures to be found at the salt marsh was tiny – the narrow-mouthed whorl snail, a threatened species only found at a handful of sites in the UK.
Birds on the conservation red list here include curlews, skylark and lapwing. All three British woodpeckers have been spotted on the hulking skeletons of the Corsican pines.
At least 150 species of plants are found on the marsh including sea purslane, sea aster, sea arrowgrass (which smells of coriander) and sea lavender.
“It’s still changing but it’s pretty much reached its full potential now,” said Benbow, who used to camp on the marsh when the seawater first came in to keep an eye on the rapid changes. “I love it out here.”
Cwm Ivy is the only site of its kind in Wales and one of few in the UK. The National Trust climate change adviser Keith Jones said: “We have allowed nature to map its own future and are now reaping benefits for wildlife. The salt marsh also proves an invaluable tool in tackling climate change by sequestering carbon.
“Obviously this type of project cannot be replicated across the UK, and we will have some difficult decisions in the decades to come, but Cwm Ivy is an excellent example of how we need to start thinking about the effects of climate change and working with it.”