"Feed the birds, tuppence a bag" croons the Little Old Bird Woman on the steps of St Paul's in Mary Poppins. But the winged critters aren't so popular with everyone; Ken Livingstone tried to eradicate them from Trafalgar Square in 2001 by banning the sale of pigeon food and hiring a hawk to maintain the pecking order. If he'd succeeded in wiping them out completely, what would London be like today? We take a look at pigeons' place in the London ecosystem.
The only creature to feast on pigeons in London is the peregrine falcon, a bird of prey that nests on the ledges of tall buildings (as this replicates their more natural environment of cliff faces), according to Matthew Evans, Professor of Ecology at Queen Mary University. The most famous pair of peregrine falcons in London nest in the chimney of the Tate Modern on Southbank, although others are known to roam the skies around Parliament and other spots.
Peregrines are adept at catching their prey when it is mid-flight (meals on
wheels wings, if you will), and London pigeons are simply a more domesticated version of the rock dove, the falcons' only source of food in other environments. Evans believes it's unlikely that an absence of pigeons would cause them to turn to another food source, such as rodents. Instead, they are likely either to die out through lack of food, or leave London and set up home in another location where their favourite meal is readily available.
In turn, this would reduce the number of greater-binocularised humans who flock to Southbank every summer in an attempt to feed their eyes on the falcons. Presumably they would be displaced to another ecosystem more accommodating to their bird-spotting needs — the Welsh coast, perhaps — freeing up more of the London space for other humans to flourish.
Looking at the food chain in the other direction, the main source of food for pigeons is human rubbish: crisps, biscuits, the odd M&S sarnie. Whatever they can get their mangled claws on, really. According to Evans, the only reason that pigeons really exist in London is due to the sheer amount of food readily available for them. So, without pigeons, this clean-up service would cease to exist, meaning we'd probably be knee-deep in half-eaten kebabs before we knew it. But excess food would soon be picked up by rats and foxes (and gulls, closer to the river), meaning we'd probably see an increase in the populations of these species.
So no pigeons in London would mean no peregrine falcons, but more rats and foxes. Think of that next time you shoo a hobbling pigeon out of your path. It's him, or a rat. And of course, fewer pigeons mean less pigeon droppings, so London buildings and statues could be free of the "lucky"* fluid, and less subject to erosion. We could also release our most sacred buildings from the protective sheath of pigeon spikes (full effectiveness demonstrated below).
*We got pooed on by a pigeon once. So distracted were we in trying to remove the muck from our new jacket that we tripped over a kerb and ended up face down in mud. Lucky our *rse.