We may frighten each other but the wild things find us tame enough

WHILE I sit here in my basement, a fox jumps through the small brown hedge. Upstairs, a sparrow flies in through the kitchen door to pick up breakfast crumbs. Grey squirrels skip across the grass. Canada geese parade like sentries by the nearby lake. Jays and magpies bustle in the trees. Herons have been sighted circling ponds. There's probably even a questing vole somewhere, feather-footing it through a plashy fen.

Sorry, this isn't supposed to be a nature column, and if all I've described were in the countryside it wouldn't be worth mentioning. But it's happening in an inner-London borough, six miles from Leicester Square. Those foxes have their earth in a suburban garden. Those geese are nesting in a council estate. Welcome to the new peaceable kingdom, the rustic metropolis.

As a child in a Yorkshire village, I used to pore over guide-books to British birds and mammals. It was my ambition to spot the rarer species - pine martens, polecats, hoopoes - and if their habitat was remote and mountainous, as it usually seemed to be, there was always the hope I'd spot them from the car on holidays. I didn't get very far: plenty of wagtails and finches, but nothing more exotic than the occasional redstart or hedgehog. At school I read Ted Hughes's poem, "The Thought Fox", which imagined "the sharp, hot stink of fox". It wasn't a smell I knew; thought was as close as I got to foxes. On Boxing Day, the local hunt gathered, red in face and coat, with such excited hounds and in such numbers it seemed certain there must be foxes about the place somewhere. I never saw one. Now I see them every day.

I'm not sentimental about nature's encroachments. Herons carry off goldfish. Squirrels are just rats with cute tails. As for foxes, they rip open plastic rubbish bags, burst plastic balls, sick up heaps of berries, steal any clothing or gardening gloves left out overnight, dig up plants, and keep us awake with their unearthly mating cries (not that they only do it at night: there's a good deal of shameless daylight rutting and knotting too). Above all, or rather underneath, there's the shit on the lawn. It may have come from a wild animal rather than a pet, but fox shit is no more pleasant to step in than dog shit.

It's no idyll. Foxes can be pigs. Yet there's an uneasy mutual respect. They have their territory and we have ours. We chuck them discarded bones, they let us watch their cubs at play. Some canter off over the garden wall if we get too near, but others - older, bolder, lolling in long grass or sunbathing on sheds - don't even bother to get up if we approach.

Darwin, in the Galapagos in 1835, marvelled at the tameness of the birds there, which would perch on human shoulders. But he also felt frustrated with their stupidity, their failure to acquire a proper terror of mankind. Twentieth-century fox, by contrast, is clever enough to know such terror is inappropriate. Since 1945, the emigration into cities has been relentless, and there are now twice as many foxes in London as in the outlying rural south-east. The pickings are richer here, square meals easier to come by: the women who might once have worn foxes round their necks now feed them bread and meat. Cars are a hazard: 50 per cent of urban foxes are run over, and whereas in captivity they can live up to 14 years, on London's streets their life expectancy is a mere 14 months. But they breed in such numbers their population is steadily growing, and it seems they feel safer away from the guns, insecticides, herbicides and open spaces. We townies speak more nicely to them than our country cousins do: we don't make them feel like vermin.

Such proximity between wild nature and busy humanity is not unprecedented. In the Bible Samson ties firebrands to the tails of 300 foxes in order to set alight and destroy the corn and vineyards of the Philistines (hence, perhaps, the creation myth that this is why some foxes look singed or mangy). But 50 years ago no one would have predicted that the fox would return to the human fold, nor that so many other species - pipistrel bats, badgers, sparrow-hawks, short-eared owls - would prosper in an urban environment.

This countrification of the city, or urbanising of nature, overthrows many inherited assumptions. Traditionally, the city has been thought the enemy of all creatures but the humans. Only the nastiest vermin, it seemed, could survive here (rats, cockroaches), and the authorities took due measure to eradicate them: the Pied Piper of Hamelin, ridding the town of rats, was a precursor of Rentokil. Domestic pets were allowed a place, on a lead or on a sofa, but for wild animals - fear of which was one of the motives for building cities in the first place - the only niche was in a cage or at the zoo. For any faintly succulent breed, the commonest fate was to be cooked and served up at the table.

Now, there's a desire to re-admit the wild, and the city is home to a variety of creatures. Some are opportunists (like the fox) or arrive by freak: a few years back there was a documentary about a family of kestrels which, outdoing King Kong, colonised the Empire State Building. Other species have to be encouraged, in specially cleared or constructed nature reserves. The London Wildlife Trust, for example, has 57 sites across the capital, and these show that there's more to London wildlife than wallabies in Battersea Park or kiddie farms with rabbits and goats. Such "management" is artificial, but it's one of the insights of the conservationist movement that nature can't just be left to go hang. In the 18th century, civilisation, the antonym of nature, meant pet monkeys and dancing bears. Now civilisation lets the buffalo roam in theme parks just outside the capital, while birds, bats, badgers and butterflies are invited in.

Meanwhile, the pest control agencies, ecologically wised up, are redefining what pests are. Nuisance to humans isn't enough of a criterion. One man's vermin may be another's deep communion with Mother Nature. When bees swarmed against my kitchen wall a few years ago, then crawled inside in hundreds up the wastepipe, no agency would touch them: though they can sting no less than wasps, bees are not classified as a pest. Exasperated but grateful, I had to find a beekeeper, who in turn had to find the queen.

Conservationists rightly insist that we've still a long way to go: one swallow nesting in the eaves of a computer firm doesn't make a summer. But the proliferation of urban species does seem to defy the rhetoric of those environmentalists who argue that an industrial or post-industrial society is necessarily hostile to nature. More, the resilience of the urban fox, or of those species whose habitat is now the motorway verge, reinstates something tough and Darwinian into ecological debate. Nature isn't always a helpless victim: it can adapt and succeed. And we humans may be less aggressive than we give ourselves credit for: those Canada geese on the council estate have not yet had their necks slit by bored teenagers.

If nothing else, those foxes down the garden are an excuse to refuse the kids a family pet: why this big need for a dog when there's so much doggy behaviour (barks, puppy-fights, leg-cocking) available just outside? At best, they inspire the hope that the world is slowly being put to rights, allowing us a modern Eden where we live and work in cities while also staying close to other species. Close but not too close: there's no better cure for soulful pantheism than a sole full of fox shit.