John James Audubon (1785–1851), The Birds of America, 1827-38. Estimate $8,000,000-12,000,000. This lot is offered on 14 June in The Portland Audubon sale at Christies in New York

‘Citizens of the feathered tribe’ — Audubon’s The Birds of America

Offered in a dedicated sale in New York on 14 June, this exceptional example of the most valuable illustrated book ever produced — and an icon of American art — was sold to benefit environmental causes

The two lanky purple herons appear to be deep in conversation. The adult bird, with its rich brown ruff, gestures with a raised blue leg as if to emphasise a point; the younger heron — its plumage still a juvenile snow-white — shrugs its rounded shoulders and keeps its bill shut. The engraving is both rigorously ornithological and strangely anthropomorphic. When you look at an engraving like this one, you have the feeling that you know these birds, that they are old friends.

This is one of the 435 hand-coloured illustrations in The Birds of America, the magnum opus of John James Audubon. He was 35 years old, bankrupt, and just out of debtors’ prison when he had his ‘great idea’. He would use his skills as an artist and a woodsman to document, as never before, the bird species of his homeland.

The undertaking would involve lengthy expeditions through North America to discover and observe all the species he could find. Audubon was setting out to create a bird collection in print, and as a collector he was a maximalist: his book was to be the catalogue raisonné of American ornithology.

It is hard to think of any other book that absorbed its creator so totally. Audubon was not just the author of the work. The years that he spent scouting and observing, painting and writing, were just the start of it. He went on to become an unstoppable one-man publishing industry, deeply involved with every aspect of the book’s production. He made several trips to Europe to find the engravers and colourists with the skills he required. While there, he travelled ceaselessly to present his portfolio to wealthy potential subscribers.

And he publicised his project by speaking at countless salons and learned societies, where he told practised tales of his adventures in backwoods America. With his flowing dark hair, his eyes (according to one admirer) ‘like an eagle’s in brightness’, and his colonial French accent, he turned out to be a fine frontman for his own endeavour. In London and Paris he seemed as exotic and attractive as the ‘little citizens of the feathered tribe’, as he called his birds.

Audubon had resolved at the start of the venture that every bird would be depicted at life size, to give readers a true impression of its appearance. It was a hugely ambitious idea — the pages would have to be enormous — but it was absolutely the right thing to do. The finished volumes of The Birds of America  were printed on ‘double elephant’, the largest size of paper then available. A bound copy measures more than a metre from top to bottom: to lift its cover is like opening a wardrobe door.

And what stunning creatures are to be found inside. Every engraving is a brilliant synthesis of artistry and zoology, of close observation and tight composition. The white pelican, for example, poses majestically in profile and fills every inch of the page. The point of its bulbous beak, the crown of its head, the soles of its yellow feet, all kiss the oblong border like the intercepts on a Cartesian graph.

Other birds in the book are notable for more sombre reasons. In 1813, Audubon witnessed the annual migration — and the mass slaughter — of millions of passenger pigeons. As he recounts in one of his anecdotal ‘Episodes’, they were tediously easy to kill. ‘The banks of the Ohio were crowded with men and boys, incessantly shooting at the pilgrims,’ wrote Audubon. ‘Multitudes were thus destroyed... The [hunters] began to move among the dead, the dying and the mangled, picking up the pigeons and piling them into heaps. When each man had as many as he could possibly dispose of, the hogs were let loose...’

Audubon believed that there was no danger to the species as a whole, because passenger pigeons were so unimaginably numerous. Yet almost exactly a century after the orgy of shooting that he witnessed, the last passenger pigeon died in Cincinnati Zoo. The Carolina parrot, beautifully illustrated in the book, was also blasted to extinction where it roosted — not because it was edible but because it was a pest: it liked to eat the fruit in farmers’ orchards.

Given that some of the American birds Audubon recorded are gone for ever, it is fitting that the sale of this complete set will benefit conservationist causes. The Portland Audubon, as this copy is known, was the property of the late Carl W. Knobloch, a lifelong outdoorsman like Audubon himself. Proceeds of the sale will go to the Knobloch Family Foundation, which is dedicated to protecting and preserving the habitats of plants and animals. Audubon once noted laconically in his journal, ‘I enjoy’d Nature’. It was a passing remark, but it could stand as an epitaph for either man.

On 14 June, The Birds of America  will be offered in a dedicated sale, The Portland Audubon, at Christie’s in New York. The Portland Audubon  is on tour and can be viewed in London at Christie’s in King Street, 19-24 May, and in New York at Rockefeller Plaza, 2-6 June.