Why the birds swept up into the skies was a mystery. Skies that had, until that moment of panic, been empty and blue except for one smudge of cloud and the bleached smoke billows from factory chimneys far across the marshes. Organised at first, the lapwings moved as a single creature. Like a sea serpent shifting its body one way and then the other, before dissolving into chaotic black fragments around a flock of starlings. We followed their wavering flight with our binoculars.
A bird of prey was one theory, though it was nowhere to be seen. But Rainham Marshes is like that: a landscape of unseen but felt presences. The Cetti’s warblers chatting, down deep in the reeds. The shoveler ducks sifting for microscopic plankton on the water’s surface. The gales that helped carry thousands of birds to this place on their flight from Scandinavia over the North Sea. The water voles, torpid in their ditch burrows.
I’d joined the regular guided bird-watching tour of this RSPB reserve, just west of the Dartford Tunnel, at a busy time of year. It was November and hundreds of migratory birds were arriving by the day. To my untrained eye, the lapwings that filled the expansive skies seemed enough to fill a small continent. But our guide Pat – a dedicated volunteer on site – explained that 6,000 of them will settle here this winter. Black-tailed godwits, widgeons, skylarks and short-ear owls from Iceland, Russia and Scandinavia will escape here too.
And what a unique escape it is, for both the birds and Londoners. One of the few remaining ancient landscapes left in the city, these medieval marshes are today 1,000 acres of protected grazing habitat; an extensive field of long and short grasses netted with ditches and a reservoir that runs alongside the Thames for a couple of miles.
Its appearance, save for the A13 and rail lines that embrace it, has been the same since a sea wall was built 500 years ago to manage the Thames’s tide, changing salt marsh to a wet marsh grassland. “When you have grass, you can feed your beasts,” explained Pat. “Hundreds of years ago, this land had a premium value for farmers, who would stop here to feed up their cattle before making the day-long journey to Smithfield Market.”
As we set off towards the reservoir, Pat pointed to what he called the reserve’s “biological lawnmowers” over in the distance. Livestock grazing is vital to maintaining species-rich habitats like this, controlling aggressive species and preventing scrub encroachment. Rainham’s lapwings – creatures of wetlands with short vegetation – are happy beneficiaries. “They don’t like the grass to be too short, as their chicks are too exposed; or too long, as they get too wet in the morning dew,” according to Pat.
Until the 1980s, the reserve was owned by the Ministry of Defence, which had used it as a military firing range and store for explosives for over 100 years. The RSPB had a long 15-year battle for ownership. Universal Studios had designs to redevelop the site into an amusement park. But the then mayor Ken Livingstone joined the fight to save the space from diggers.
We settled behind some reeds with our binoculars, metres from the reservoir. As Pat adjusted his scope on a small flock of dunlin at the water’s edge, a Eurostar clattered past, its carriages smeared with the smog of a thousand journeys. “We have rail, road and ships nearby and we’re close to City Airport too. But being such a large reserve, it is big enough for the wildlife not to be worried,” said Pat.
Looking out across the water suggested as much. The pond was a world apart from its edgelands. Snipe skulked in the marshy fringes, dabbing their pencil-like bills about. Pochard, widgeon and shelduck mingled like fairground bumper cars. Their only concern the bulky cacophony of fuss being created by a flock of greylag geese that had just settled on the water.
There are no shortage of reminders of Rainham’s military past. Crumbling target ranges are now the preserve of moss and birds, and the ridges of grass across the site, where rifleman practiced, now serve to separate the landscape into distinct habitats. But the migratory species that have made the journey here this winter were also here as German Second World War bombers scoped the site on their way up the water to the city, and they were probably here before that as well.
We positioned ourselves along the boardwalk, a creamy light washing over the reserve and throwing the birds into shadow, making it hard to distinguish one species from the next. The reflections of two stripes of plane exhaust fumes appeared in a cross on the surface of the water. A flock of dunlin rose up, swishing one way and then the other, flashing white then grey like a shoal of fish. “Now you see me, now you don’t,” said Pat, marveling at their shimmering display.