I once was given an otter skull to hold. The strangeness of cool bone filled my palm. Sharp canines, flattened crown, broad eye sockets. It was more streamlined than any other animal skull I’d seen. I felt kinship stirring within me. Then I was given a copy of Henry Williamson’s Tarka the Otter to read. For months afterwards I felt part-otter, and my life was never quite the same.

Although in the south-west of England we are familiar with what is now called Tarka Country, many people may never have read Williamson’s book. This area of North Devon has been designated the UK’s first UNESCO Biosphere Reserve due to its uniquely rich ecosystem, partly thanks to the influence of Williamson’s writing.

The poetic description, the tenderness, truth and acute observation in Willliamson’s work put the landscape of North Devon under the microscope. The passage from the opening of the book, a description of the birthplace of Tarka, invites the reader into a place that can still be experienced today: “Twilight upon meadow and water, the eve-star shining above the hill, and Old Nog the heron crying kra-a-ark! as his slow wings carried him down to the estuary. A whiteness drifting above the sere reeds of the riverside, for the owl had flown from under the middle arch of the stone bridge that once carried the canal across the river.”

Williamson was a self-taught naturalist, and he regularly took his children on expeditions to Braunton Burrows, on the coast, to spend whole days identifying and counting the vast diversity of species that occurred there. His profound knowledge of the ecology of the region suffuses his writing.

Every one of our senses is called forth in his evocation of the delicate web of life: “Time flowed with the sunlight of the still green place. The summer drake-flies, whose wings were as the most delicate transparent leaves, hatched from their cases on the water and danced over the shadowed surface. Scarlet and blue and emerald dragonflies caught them with rustle and click of bright whirring wings. It was peaceful for the otters in the backwater, ring-rippled with the rises of fish, a waving mirror of trees and the sky, of grey doves among green ash-sprays, of voles nibbling sweet roots on the banks.”

Detailed observations of the land are brought into sharp focus: “To the estuary came sanderlings in white winter dress, who ran at the tide-line like blown sea foam. Snow buntings followed, and went south with them…”

A perfectionist, Williamson said that he strove to produce writing that was true and compelling; each word, he claims, was “chipped from the breastbone”. Ted Hughes described him as “one of the two or three truest poets of his generation”. Hughes remarked that when he read Tarka as an eleven-year-old, it “entered me and gave shape and words to my world, as no book has ever done since…” It was “something of a holy book, a soul book, written with the life-blood of an unusual poet”.

Again and again, Williamson teases out our sympathies with the delicate suggestion of imagery. In this passage Tarka loses a sister to a trap: “While the otter tore with her teeth at the chain, the spring, and the closed jaws of the gin, Tarka and the other cub ran among oak saplings, rustling the buff leaves of an old year, and breaking the stalks of seeded bluebells whose caps dropped round black seeds to the earth.”

Designed to awaken, this prose is almost shamanic in its intensity. Williamson presents an otters’-eye view of the meandering calligraphy of the water, its banks, reeds and wetlands. It is concerned with small detail: reeds iced like filaments in winter, a dragonfly alighting upon a leaf, a water beetle bending the surface of the water with its feet. The river is often given the properties of an animal, where “the pool quickened smoothly into paws of water, with star-streaming claws”.

At the end of the novel, published in 1927, Williamson presents his ‘original’ ending, which disappeared in the editorial process of publication. The words leave us in no doubt as to how the author felt: “Something was taken in a salmon net hauled by four fishermen on the gravel ridge in the estuary… The head of the otter was pierced and crushed by the jaws of hounds, its rudder and hind legs were broken, one forepaw was maimed. The skin was of no value, as the animal had been dead a long time. The fishermen dropped the body over the gunwhale as they rowed home, and the sea received it tenderly, like something loved that had been lost, and found again.”

Williamson claimed that he could feel what the otter felt, but all the time retained a respectful humility towards the natural world, explaining, “This hand may have held the pen, this mind may have shaped the narrative – but of that which arose out of my living I felt then, and feel today, I am but a trustee. To forget that trusteeship ... is to cease to be a writer.”

The tale of Tarka shows the harsh reality of a time when the otter was hunted mercilessly close to extinction. It has been marketed as a children’s book, but is far from it. Every bend in the river Torridge, every landmark of the Taw is described, and along the way, the path of Tarka’s short life. Although the otter was not protected until many years after the story was published, Williamson’s message has had a profound effect on our consciousness. Today, the otter has become an icon of nature conservation.

It is over eighty years since this classic book appeared. Inspired by his father’s work, Harry Williamson, composed The Tarka Symphony with former Genesis guitarist Anthony Philips. A modern work in three movements, it mirrors the life cycle of the otter and the flow of the rivers Torridge and Taw through North Devon. It will be performed for the first time in February 2010, in Melbourne – where Harry Williamson now lives – before coming home to audiences in Tarka Country. The symphony is a musical tribute to two distinctive ecological regions, the Braunton Burrows Biosphere in North Devon and the Mornington Peninsula Biosphere in Australia.

A founder member of the Green Party, Harry has composed something he hopes will affect the way we feel and see the beauty of the world around us and move us to action. The name Tarka means ‘wandering as water’, and what better emblem for this project – which was created to remind us all of the importance of water conservation – than the otter, an animal that represents both fragility and hope?

Miriam Darlington is a poet. Her poetry collection Windfall is available from Oversteps Books.