On the Arne peninsula in Dorset, the gnarled heather and gorse gives way to a soft sand beach gently lapped by the opaque waters of Poole harbour.
But as a flock of oystercatchers graces the skies above this globally significant ecological site, an unsettling anxiety pervades the otherwise tranquil idyll.
Just over a mile along the coast, over precious salt marshes and mudflats, a pipeline from Wytch Farm, the largest onshore oilfield in Europe, leaked on Sunday, spilling 65 tonnes of “reservoir fluid” – a brine mix containing oil – into the waters.
As the oil belched into Owers Bay on Sunday, a male osprey returned to Poole harbour from west Africa to nest, his distinctive white and brown plumage delighting birdwatchers on the ground and online. His mate is expected to arrive in April; they bred for the first time in 2022, becoming the first pair to do so after an absence of nearly 200 years.
The moment of celebration soon turned bittersweet as sinister, filmy slicks were blighting the surface of the natural harbour on Monday, with a major incident declared and a clean-up operation launched.
The RSPB – which protects 250 hectares (630 acres) and six miles of coastline on Arne – has already identified birds covered in oil, including shelducks, Mediterranean gulls and black-headed gulls.
On Shipstall Hill above the shoreline, Peter Robertson, senior sites manager at RSPB Arne, points to a passage of water between the privately owned Round Island and the peninsula where a slick was spotted earlier in the day, perilously close to the salt marshes that provides a habitat for thousands of wetland birds.
“We have black-tailed godwits, avocets, curlews, spoonbills, they all occur in nationally important numbers,” Robertson says just before a large flock of brant geese noisily glide past, landing on the tip of nearby Long Island.
That an oil leak can occur near Arne confounds Robertson. Poole harbour, he explains, is one of the most heavily protected natural areas in the UK, with protections at UK, European and global level.
“One of the most important wetlands in the world, with the highest level of protection, yet it is still at severe risk,” he said.
The spill could not have happened at a more critical time in the year for Arne and the wider harbour. As the seasons turn, the wetlands are uniquely home to winter birds yet to depart and summer birds recently arriving. “We’re at peak traffic,” Robertson says.
The birds are not the only wildlife at risk. Poole harbour and its surrounding environs are a fragile, complex ecosystem.
The marshes and mudflats are abundant with invertebrates and shellfish, a vital source of food for the birdlife, while the waters are full of fish, including bass, mackerel, tope – all sustenance for ospreys and the equally rare white-tailed eagles that soar above the harbour’s waters.
Robertson, his colleagues and volunteers will be out on the Arne shoreline over the next week and beyond monitoring the impact of the leak from the Perenco-operated onshore oilfield, the largest in Europe.
Using binoculars, they will be looking for discolouration of feathers and a distinctive sheen left by oil.
“This isn’t crude oil, so the images that might come to mind of birds battling thick black sludge isn’t what’s happening here, but we have seen oiled birds,” Robertson says.
With bird flu at pandemic proportions, particularly hitting seabirds, this is another potentially devastating challenge the wildlife could do without.
And with David Attenborough’s latest BBC series, Wild Isles, putting renewed focus on the importance of protecting and preserving natural habitats in the UK and beyond, Robertson agrees the leak comes at a time of acute awareness of the fragile state of the environment.
The salt marshes surrounding Poole harbour, for example, absorb the heat-trapping gas carbon dioxide, he adds.
“We are in the midst of a global biodiversity and climate crisis,” Robertson says. “Nature-based solutions are key.”
Leaving the Arne peninsula along a narrow dirt track, two men kitted out in Environment Agency fleeces are walking towards the shoreline, empty plastic bottles in hand, braced to test the waters.
Perenco insists the leak has been contained but the true impact of this tragedy for nature may not be fully realised for months and even years to come.
