Of all the reasons to fall in love with London, there are two that, for me, transcend all others. Firstly, and perhaps most obviously, is the city’s rich and enviable diversity. Whether you’re a native or (like many of us) an adopted son or daughter, London fosters a fascination with the unfamiliar.
Secondly, it’s the capital’s inherently transient dynamic. London’s true essence is ephemeral. Like the river it clings to for dear life, its communities and populations ebb and flow, constantly rejuvenated and reshaped by new waves and changing tides.
Now try thinking of these things in relation to the hundreds of other species we share our city with. They apply just as potently to an epic, endlessly fascinating story that few of us are intimate with but is playing out around us, throughout the spring, autumn and beyond, day and night – bird migration.
Most of us know something of it on a wider scale, perhaps as transmissions from far-flung, exotic locations, delivered in high definition to our living rooms. Some of us may have brushed against it directly, looking up to see disorderly skeins of geese following the coast, or pausing to watch a sky full of swallows hawking expertly over a local lake.
Relatively few of us, however, are aware of its significance and extent on our doorsteps. Enjoying it first-hand is by no means a specialist exercise confined to a few exclusive places. On the contrary, anyone can connect with this traditionally secret world simply by taking an early morning walk in a local park at the right time of year, or even just looking up for long enough.
The movement of birds in, over, through and around the capital is a complex business, occurring throughout the year and for a variety of reasons. In the height of summer, for example, young birds disperse from their natal areas, often in initially random directions; in the dead of winter, meanwhile, London receives more than its fair share of refugees fleeing frozen conditions on the continent, seeking sanctuary and a comparatively mild climate.
But broadly speaking, avian migration is inextricably linked to spring and autumn. In the spring it’s essentially a northbound movement and in the autumn, essentially southbound. While most of us are busy struggling to make it through the seemingly endless depths of the late winter, this magical annual phenomenon has already begun in distant places around the world, and it’s only a matter of weeks before the vanguard reaches London.
The migratory species that frequent our city are a rich and varied clan, from tiny, insectivorous warblers to powerful, impressive birds of prey and everything in between. They utilise a broad spectrum of skills and aids to navigate successfully, many to the same place, year after year and generation after generation. One such skill is the use of traditional flight lines and visual aids.
Hence, an osprey bound for a solitary loch in the Scottish Highlands, and crossing London en route from its African wintering grounds, may follow a flight path deliberately plotted not only according to natural landscape features such as rivers and valleys, but to human-made features like buildings and roads. Hard to believe as it may be, the slide rule, Roman-built A10 out of Liverpool Street can be as important a navigational aid to a long distance migrant as the relative positions of Taurus and Cassiopeia in the night sky.
Various habitats within the city are valuable refuges for migrants, be it for a few hours or for a whole summer. From a migratory bird’s perspective, expansive, truly urban areas are effectively deserts, unwelcoming and fraught with danger. But, despite massive losses over the recent times, London is still blessed with a comparatively large variety and combined area of semi-wild spaces and green oases.
Flagship reserves (including the Wetland Centre and Rainham Marshes) justifiably spring to mind, but crucially London is also blessed with an archipelago of islands in the concrete ocean – from the heart of the city to its suburban fringes – that make it arguably one of the greenest major cities in the world, and a great place to enjoy and nurture birdlife.
To multitudes of tired, hungry migrants, the sanctuary of our parks, woodlands, wetlands, gardens, brownfield sites and other semi-natural habitats is absolutely critical, however modest or isolated they may seem. And any habitat that has escaped development, by accident or design, is of more value than ever in these dark days of short-termist, blinkered profiteering.
To a spotted flycatcher, for example – a barely Robin-sized, long-distance migrant that travels thousands of miles to reach the UK every spring – the woodland glade habitat recreated by rows of adjoining back gardens can be both a temporary life-saver and a place to set up the family home. To a whimbrel bound for the Scandinavian tundra, meanwhile, the bountiful mudflats of the Thames are as essential as the marshes of the Camargue.
While most of the Thames’ formerly expansive floodplains and marshes have long since disappeared under the bulldozer, what remains – a precious estuarine environment still teaming with multitudes of waders and wildfowl – is not only of unrivalled local importance, but is an essential piece of a uniquely valuable jigsaw.
Come autumn, anything can happen. Countless thousands of migrants – the majority young and inexperienced – employ a bewildering array of navigational aids to lead them towards their winter quarters and find themselves moving over, through and into London.
In contrast to the spring migration, autumnal movements are more prolonged and meandering and involve many more individuals. Hence, possibilities are blown wide open and the floodgates remain open from the late summer to the early winter.
That London is both a valuable pit-stop and a crucial final destination for so many intrepid, highly-skilled travellers is something to celebrate, cherish and protect. And it’s worth remembering that the capital’s enviable capacity to accommodate, integrate and welcome myriad new arrivals is by no means reserved for noisy bipeds.
© Mark James Pearson 2012