non-human life around us. Before I was a writer I was a historian of science, which was an eye-opening occupation. We tend to think of science as unalloyed, objective truth, but of course the questions it has asked of the world have quietly and often invisibly been inflected by history, culture and society. Working as a historian of science revealed to me how we have always unconsciously and inevitably viewed the natural world as a mirror of ourselves, reflecting our own world-view and our own needs, thoughts and hopes. Many of the essays here are exercises in interrogating such human ascriptions and assumptions. Most of all I hope my work is about a thing that seems to me of the deepest possible importance in our present-day historical moment: finding ways to recognise and love difference. The attempt to see through eyes that are not your own. To understand that your way of looking at the world is not the only one. To think what it might mean to love those that are not like you. To rejoice in the complexity of things.
Science encourages us to reflect upon the size of our lives in relation to the vastness of the universe or the bewildering multitudes of microbes that exist inside our bodies. And it reveals to us a planet that is beautifully and insistently not human. It was science that taught me how the flights of tens of millions of migrating birds across Europe and Africa, lines on the map drawn in lines of feather and starlight and bone, are stranger and more astonishing than I could ever have imagined, for these creatures navigate by visualising the Earth’s magnetic field through detecting quantum entanglement taking place in the receptor cells of their eyes. What science does is what I would like more literature to do too: show us that we are living in an exquisitely complicated world that is not all about us. It does not belong to us alone. It never has done.
These are terrible times for the environment. Now more than ever before, we need to look long and hard at how we view and interact with the natural world. We’re living through the world’s sixth great extinction, one caused by us. The landscapes around us grow emptier and quieter each passing year. We need hard science to establish the rate and scale of these declines, to work out why it is occurring and what mitigation strategies can be brought into play. But we need literature, too; we need to communicate what the losses mean. I think of the wood warbler, a small citrus-coloured bird fast disappearing from British forests. It is one thing to show the statistical facts about this species’ decline. It is another thing to communicate to people what wood warblers are, and what that loss means, when your experience of a wood that is made of light and leaves and song becomes something less complex, less magical, just less, once the warblers have gone. Literature can teach us the qualitative texture of the world. And we need it to. We need to communicate the value of things, so that more of us might fight to save them.
When I was small, I decided I wanted to be a naturalist. And so I slowly amassed a nature collection, and arranged it across my bedroom sills and shelves as a visible display of all the small expertises I’d gathered from the pages of books. There were galls, feathers, seeds, pine cones, loose single wings of small tortoiseshells or peacock butterflies picked from spiders’ webs; the severed wings of dead birds, spread and pinned on to cardboard to dry; the skulls of small creatures; pellets – tawny owl, barn owl, kestrel – and old birds’ nests. One was a chaffinch nest I could balance in the palm of my hand, a thing of horsehair and moss, pale scabs of lichen and moulted pigeon feathers; another was a song-thrush nest woven of straw and soft twigs with a flaking inner cup moulded from clay. But those nests never felt as if they fitted with the rest of my beloved collection. It wasn’t that they conjured the passing of time, of birds flown, of life in death. Those intuitions are something you learn to feel much later in life. It was partly because they made me feel an emotion I couldn’t name, and mostly because I felt I shouldn’t possess them at all. Nests were all about eggs, and eggs were something I knew I shouldn’t ever collect. Even when I came across a white half-shell picked free of twigs by a pigeon and dropped on a lawn, a moral imperative stilled my hand. I could never bring myself to take it home.
Naturalists in the nineteenth and early twentieth centuries routinely collected birds’ eggs, and most children who grew up in semi-rural or rural surroundings in the 1940s and ’50s have done it too. ‘We only used to take one from each nest,’ a woman friend told me, abashed. ‘Everyone did it.’ It’s simply an accident of history that people two decades older than me have nature knowledges I do not possess. So many of them, having spent their childhoods bird’s-nesting, still see a furze bush and think, Linnet, and can’t help but assess the ability of last year’s laid hedge to hold a chaffinch or robin’s nest. They possess different wordless intuitions from me, ones relating to how one holds the landscape between head and eye and heart and hand. In my own history of the countryside, nests weren’t things that were made to be found. They were carefully maintained blind spots, redacted lines in familiar texts. But even so, they had special salience when I was very young. For children, woods and fields and gardens are full of discrete, magical places: tunnels and dens and refuges in which you can hide and feel safe. I knew, when I was small, what nests were about. They were secrets.
I followed the flights of blackbirds and tits and thrushes and nuthatches through my garden. And every spring their nests changed how I felt about home. To have the presence of these birds shrunk down to that one point of attachment, the nest, made me anxious. It raised questions of vulnerability, made me worry about predatory crows and cats; made the garden a place of threat, not safety. Though I never searched for nests, I’d find them all the same. I’d be sitting at the kitchen window eating a bowl of Weetabix and I’d spot a dunnock flit into the forsythia, a mouse-sized bird, all streaks and spots and whispers. I knew I should look away, but I’d hold my breath at my transgression and track the almost imperceptible movement of leaves as the disappeared bird hopped up and across through twigs to its nest. Then I’d see the blur of wings as the bird slipped free of the hedge and was gone. And once I’d determined where it was, and saw that the adults were gone, I needed to know. Most of the nests I found were higher than my head, so I’d reach my hand up and curl my fingers until their tips touched what might be warm, glossy smoothness. Or the unbearable fragility of small flesh. I knew I was an intruder. Nests were like bruises: things I couldn’t help but touch, even though I didn’t want them to be there. They challenged everything that birds meant for me. I loved them most because they seemed free. Sensing danger, sensing a trap, sensing any kind of imposition, they could fly away. Watching birds, I felt I shared in their freedom. But nests and eggs tied birds down. They made them vulnerable.
The old books on birds that lined my childhood shelves described nests as ‘bird homes’. This confused me. How could a nest be a home? Back then I thought of homes as fixed, eternal, dependable refuges. Nests were not like that: they were seasonal secrets to be used and abandoned. But then birds challenged my understanding of the nature of home in so many ways. Some spent the year at sea, or entirely in the air, and felt earth or rock beneath their feet only to make nests and lay eggs that tied them to land. This was all a deeper mystery. It was a story about the way lives should go that was somehow like – but not anything like – the one I’d been handed as a child. You grow up, you get married, you get a house, you have children. I didn’t know where birds fitted into all this. I didn’t know where I did. It was a narrative that even then gave me pause.
I think differently of home now: it’s a place you carry within you, not simply a fixed location. Perhaps birds taught me that, or took me some of the way there. Some birds’ nests are homes because they seem indivisible from the birds that make them. Rooks are rookeries – birds of feathers and bone that are also massed assemblages of twigs in February trees. House martins peering from the entrances of their nests under summer gables are beings of wings and mouths and eyes but also all the architecture of gathered mud. But some birds’ nests seem so far from nests at all that the word itself drifts and almost loses purchase. The form of one such nest is: chips of old rock and bones and hardened guano, where the overhang supplies shade. The form of another is: a raft of weeds that rises and falls with the ebb and flow of water. Another: a dark space under roof tiles where you can crawl on your mouse feet and your wings drag like feathered blades the colour of carbon steel. Peregrine. Grebe. Swift.
Nests increasingly fascinate me. These days I wonder about how they seem to be one kind of entity when they