Burt met us at Abergavenny station. I had my cub with me: Tom, aged eight. Badgers are highly sociable, familial creatures. A lone badger is unthinkable. And Tom, who is profoundly dyslexic and therefore gifted with a dazzlingly holistic, intimately relational view of the world, is, I’d guess, far closer to being a badger than I am. Also, Tom is 4ft 6in. I’m 6ft 3in. Ferns brush his face as they brush a badger’s.

We piled into Burt’s Land Rover and went to the farm. I had thought of enlarging a disused sett, but I wasn’t confident of persuading the police that I wasn’t badger digging, and I didn’t like the idea of inhaling, along with the good earth of mid-Wales, a huge dose of TB bacilli. Burt’s JCB couldn’t give us a tunnel, just a deep trench scored into the hill, but it worked very well. We covered the roof with branches and bracken, and sealed it with earth. Burt chugged off down the valley for fishcakes and left us to it. We wriggled inside and tried to be a bit more authentic. We shaped the sett with our paws and a child’s beach spade. We tried to scuffle out the earth with our hind legs, but couldn’t, because the ceiling was authentically low. Tom could pull the bracken bedding in backwards, like a proper badger, but it was too much for me.

And we sneezed: constantly, mightily and unbadgerishly. Badgers seem to have some sort of muscular sphincter just before the entrance to the nostrils that they can close when they’re digging to stop the earth getting in. But we haven’t, and in that dry July, it was terrible. When they’re hunting, nose to the ground, badgers can’t use that merciful sphincter: they need to catch the scent, so they blast out the dust in heavy snorts. That, between sneezes, is what we did as we excavated. Tom was filling tissues with silica and blood for a week.

We used head torches. Badgers have more photoreceptive rods in their retinas than we do and a reflective layer in their eyes, called a tapetum, which makes them shine in car headlights; they squeeze more light from their world than we do. The near dark of our midday tunnel would have been dazzling to them.

‘This world was more interesting than my own. A lot more happens at six inches and below than at six feet and above.’ Mask supplied by the Guardian. Photograph: Felicity McCabe/The Guardian

We crawled down to the river, lapped from a pool where leeches waved at our lips, and crawled back to our chamber, where we fell asleep, side by side and head to toe, as all good badgers do. But Tom always moved in the night. “Feet in the face aren’t friendly,” he said.

We awoke to the rattling of a jay and the growling of an engine. It was Burt, with fish pie. “Bogus, I know, but I won’t tell anyone.” In fact, it wasn’t bogus at all. Badgers are the ultimate opportunistic omnivores. No badger would turn up its nose at fish pie. “I’ll tell you what, though,” he went on. “To compensate, I’ll come down later and set the dogs on you. And then we’ll go up to the road and I’ll try to run you over.”

We stumbled up the bank and hollowed out a nest in the bracken. Lying up outside the sett during the day isn’t unbadgerish, although it’s far from the rule. Badgers sometimes, just like we did, crawl into dense vegetation and lie there until dusk comes. We don’t know why; perhaps there’s tension at home and they can’t bear the thought of a day close to wretched, cantankerous, odious X. And sometimes, no doubt, they’ve been caught short a long way from home and don’t want to run the gauntlet of early-morning dog walkers.

Tom needed to sleep, so he did, curled foetally on bracken, his paws, earth-brown from digging, clasped under his chin. I, too, needed to sleep, so I didn’t. We had to change our rhythm to that of the badgers, which meant sleeping in the day, but, at least at first, I found the sett a threatening place. Was this an old fear of burial? A worm fell into my mouth. I gagged quietly and went back to sleep.

We shaped the sett with our paws and a child's beach spade. We tried to scuffle out the earth with our hind legs

Those first few days taught me a lot. They taught me that, despite my shaggy, anarchic pretensions, I was dismally suburban: I preferred a whitewashed wall to the endless fascination of a real earth one. I preferred my ideas of badgers and the wild to real badgers and real wilderness. They were more obedient and less complex. And they didn’t broadcast my inadequacies so deafeningly.

But I learned to like that burrow. Habit is tremendously powerful. Merely having a place at the end pressed to the shape of my body was enough to change my appetite for underground living. From that low platform, I could jump to more complex forms of appreciation: the shape of the window on the sunlit world that was the tunnel’s end; the exuberant spectrum of smells as I crawled up through a cervix of earth and leaf mould and out, panting from the effort. It was OK to lie in the dark, surrounded by the scratching and humming and thrashing of animals that would one day eat me. Quite a lot of being a badger consisted simply in allowing the wood to do to us what it did to a badger: being there when it rained; keeping badgers’ hours; letting bluebells brush your face instead of your boots.

But there were some high physiological fences keeping us out of the badger’s world. The main one was scent. My landscape is a visual one. The badger’s territories are marked by defecation, and the faeces of each badger carry a unique scent. But noses don’t just map perimeters: they sneeze form, colour and personality into the badger’s life. For a badger, with its relatively poor eyesight, wood sorrel is mainly the scent of wood sorrel; a dead hedgehog is the shape of hedgehog.

In my time away from the sett, I tried strenuously to turn myself into a more olfactory creature. I joined a blind-tasting wine society. I held blind smellings of my children’s clothes. I snipped off different types of leaves each day and put them on the pillow at night. But, most of all, I lay outside with my nose on and at various levels above the ground, learning how scent changes through the day, the seasons and over the immense distance between the ground and the normal elevation of my nose.

A few days after dumping us, Burt roared back with chorizo and news. The news was about some figures on some national balance sheet, and about an imminent storm. I couldn’t have cared less about the figures, but I did care about the storm.

“Remember,” Burt said as he climbed into the Land Rover, “you’ve got to be naked: butt naked.” He was wrong. Badgers have a thick outer coat of coarse hair over a softer inner layer. Both trap air very efficiently. To strip off would take me a long way from the badger’s sensory world. I was much closer to it in my old moleskins and tweed coat. In which, as soon as Burt had gone, I went to sleep.

We had not been in the wood long, but already it was ours. I’d thought that it would seem an absurd pretension to go on hands and knees through the wood. Now it would have seemed an insufferable arrogance to do otherwise. Our heads swayed from side to side – exactly the questing swing of a badger, but forced by our clumsy anatomy. I was handling the badger’s world with thick mittens. But even so, this world was more interesting than my own. A lot more happens at six inches and below than at six feet and above.

We bustled and grunted and elbowed and pushed and pressed our noses into the ground. When the rain came, it split the ground open. Scent came spinning out, as if the ground were bursting to tell the story of that summer. Earthworms dripped from the hill like mucus candles from a snotty-nosed child.

‘Quite a lot of being a badger consisted simply in allowing the wood to do to us what it did to a badger: being there when it rained; keeping badgers’ hours; letting bluebells brush your face instead of your boots.’ Photograph: Felicity McCabe/The Guardian

I lay at the mouth of the sett. It had a curtain of water, like those curtains of beads that fill the doors leading to the toilets in small Chinese restaurants. It was almost totally dark, except when lightning bled through the fault lines in the sky. The whole wood bent to the wind. We rocked in our cradle, the roots around us straining and creaking like the timbers of a rolling ship. A wood mouse, displaced from a flooded or crumbling tunnel, scrambled in and hunched, shivering, in the crook of Tom’s knee. The mouse reassured me. We were in the best place, a sanctuary accredited by the wild, so I snatched bits of queasy maritime sleep. Tom slept, which is what I expect badgers do in storms.

But Nova Scotia’s worst wasn’t so bad. Our sett wasn’t damaged at all but, out of gratitude to it, and with a new pride in having survived the worst, we set to that morning to make it even better. We excavated a new chamber, complete with shelves, reinforced the roof and built an imposing earth arch at the entrance. Then, as Tom was happily making his own purely recreational earthworks, I slipped into unbroken sleep.

You'd have thought that trees close to each other would smell alike, but it wasn't so

Burt trundled back, not looking as solicitous as he should have been after leaving his supposed friend and a cub in a wood in an historic storm. This time it was lasagne.

Food worried me. I couldn’t duplicate the precariousness of the badger’s life. We did our best: we ate earthworms, both raw and cooked, and any other flotsam tossed up by the valley that we could keep down. We scraped a squirrel off the road and had it with wood sorrel and wild garlic. But there were Burt’s regular gifts, which we had neither the discipline nor the churlishness to refuse, and lying guiltily at the bottom of the backpack were sardines, tuna and beans. “It’s ridiculous to think you can know this wood like a badger,” Burt said a week or so later. “You can’t even know it like me. A man whose DNA has been sloshing round this wood for half a millennium knows more about a badger’s world than someone who sniffs and slithers for a few weeks.”

I was annoyed. I was determined to take one part of the wood – the badger’s part – from Burt. It shouldn’t be hard, I thought. He’s just a man. I’m halfway to being a badger.

Burt’s nose has been devastated by years of roll-ups, and his brain by generations of agricultural reductionism. We’d been in hard olfactory training with lumps of cheese, our noses were a badger’s height from the mulch, and we were humble. We could quickly overtake his ancestral understanding of the land with our specific olfactory wisdom.

Over several squirming, scraping weeks, we made our own map of the wood: a scent map. You’d have thought that trees close to each other would smell alike, but it wasn’t so. We could mark our blindfolded crawls fairly well using just the nearby oaks: “Out of the tunnel, turn right. Fifteen yards; raw tobacco, mostly Turkish; straight on. After half a minute, wall of limes and sick in front. Resolves into oranges rubbed on leather to your left and mushroom risotto with too much parmesan to your right.”

Once, as we were watching ladybirds mash aphids, Tom said, “I can smell mice” and he set off along a new path, swimming breaststroke through the grass. He was very nearly right. He’d smelled and uncovered a network of bank vole runs, marked by droppings, fine-chopped stems and urine. But what was more interesting was how he hunted. He sniffed very fast – several snuffles a second. This, I later learned, is precisely what scent-reliant mammals do.

Tom had mercifully few of my inhibitions. He licked slugs (“The big black ones are a bit bitter, and the bigger they are, the bitterer they are: I prefer the browner ones; they’re sort of nutty”), crunched up a grasshopper (“Like prawns that taste of nothing”), had his tongue bitten by a centipede and his nose invaded by ants, and sucked up earthworms like spaghetti (“The big ones are hairy, and I don’t like that so much”).

‘To thrive as a human being I needed to be more of a badger.’ Photograph: Felicity McCabe/The Guardian

All of him inched smoothly towards badgerhood. His achilles tendons stretched and his wrists and neck tightened so that he could frolic four-footed through the fern arcades. He swore he could hear a woodpecker’s tongue being thrust through holes in tree bark. “I can, you know. Imagine a nail file whispering.”

Of course, we never began to know the wood as Burt did. Yet, even in our short time there, we started to seep into it, and it into us. We got calluses where it was good to get them; our legs learned to stretch to slide easily over a fallen beech. We heard the real badgers every night as they crashed through the bracken, and occasionally got a Belisha flash of head stripes or a darkening of a shadow as a badger lumbered into it. We’d often try to approach them and got good at hearing them pause, then putting their fears to rest by loudly scratching ourselves. We put our front paws on trees and stretched as soon as we came out of our hole. We defecated on mounds chosen for their view of the hill. We acquired a thick patina of scent that even Burt, his nose full of lanolin and diesel, could know and resent.

Burt’s jibes and meals became less frequent. We were left on our own to be encrusted by the valley. We saw strange lights in a long-abandoned house. Our hackles rose when we heard farm dogs. We put a badger’s skull on a stick outside the sett for no reason I can identify clearly. A wren speared a caterpillar on Tom’s leg as he lay snoring in a clump of dead bluebells. My watch seemed offensive: I took it off, put it in a bag and ceremonially buried it. And, for that summer, we had to be content with that: with knowing that, in some ways, perhaps for a few minutes, we had lived in the same place as some badgers.

We went back to Abergavenny station, thinking that we’d failed. The town blared, belched, leered and cackled. I felt sick from shock and boredom and the heaving floors of deafening smell. Someone asked me the way to the cashpoint. It seemed as if he was shouting at the top of his voice, nose to mine. I jumped through the roof and nearly knocked him down.

I was desperate to get back to the valley. On the train, I put in earplugs and looked at the fields sliding past – the distances hideously shortened by the engine. Then I took out the earplugs and listened to a recording of woodland birds. I was missing something that I very urgently needed – something I had recently had. To thrive as a human being I needed to be more of a badger.

• This is an edited extract from Being A Beast, by Charles Foster, published on 4 February by Profile Books at £14.99. Order a copy for £11.99 from the Guardian bookshop