Recently in The Independent we summarised the 10 years of our campaign to save the house sparrow, which has largely disappeared from central London for reasons which remain a mystery. In terms of sparrow stories, this vanishing act is hard to beat. Yet there is another sorrowful sparrow tale which is up there with it, in terms of drama, and which bears retelling.

Fifty-two years ago, Mao Zedong, Chairman of the Central Committee of the Communist Party of the People's Republic of China, decreed that all sparrows in the country were to be killed. He had decided China was to make a sudden surge in its economic development, which came to be called The Greap Leap Forward, and sparrows, which Mao thought ate too much grain, were getting in the way.

The bird concerned was not our house sparrow, Passer domesticus, but its close relative, our tree sparrow, Passer montanus, which in China replaces the house sparrow as the bird which lives with people, hangs around houses, hops about gardens, cheeps from hedges and is generally an ever-present crumb-pecking part of the urban scene. China's sparrows have always been regarded with tolerant affection – they were a favourite subject of Chinese painters for centuries – but in 1958 Chairman Mao decided they had to go.

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We remember that Caligula made his horse a consul; that was merely madness. Of all the egregious acts of dictators, down through the centuries, Mao's sparrow death sentence is in a weird class by itself, not just for its scale, or its ruthlessness, but because in his own terms it was rational, a logical consequence of the pursuit of scientific socialism, and he possessed the means to carry it out – 600 million people who would obey his every whim – yet it was delusional entirely.

The delusion was that he could conquer nature. One of the most striking aspects of Mao Zedong's personality, which has left a poisoned legacy in China, was his attitude to the natural world: it was from start to finish adversarial. Not for him the ancient Daoist tradition of living in harmony with the forests and mountains and lakes and rivers, and the creatures they contained. Nature was not there to be respected; it was simply a resource to be used, and the mountains and rivers were to be mastered; they were to be bent to man's will. "Make the high mountain bow its head; make the river yield the way," Mao said in 1958. His slogan was Ren Ding Shen Tian: Man Must Conquer Nature.

His efforts to do that in The Great Leap Forward, through grotesquely misapplied agricultural policies, led to famine in which perhaps 30 million people died, and the affair of the sparrows might seem trivial in comparison, were it not for what it represents.

Nobody knows how many there were in China in 1958, but if there was one for each person, which seems reasonable, there would have been 600 million. Mao really tried to get rid of them all. He mobilised the entire population, who not only shot them and destroyed their nests but went out every evening with gongs and pots and pans to bang, so the birds would have nowhere to settle and roost, and would eventually die from exhaustion.

Millions of sparrows, maybe hundreds of millions, were killed. But the following year, 1959, it was noticed that insect infestation of crop fields had soared; pests such as locusts, which the sparrows ate, had lost a major predator. China's Academy of Sciences produced reports on how many insects the birds ate, compared to how many seeds, and it became clear that killing sparrows was cruelly counter-productive; presented with the evidence, Mao called it off, but not before the already failing harvest had been even more reduced right across the country.

It was one of history's most notable acts of hubris over the natural world. I retell the episode because for the past week I have been in China, attending a British Council symposium on climate change and the media with Chinese journalists in Shanghai, and the vivid impressions of the astonishing city which is fast becoming the Paris of Asia have been mixed with an unquenchable curiosity: would I see any sparrows?

For three days I scanned every street food stand, every boulevard tree, every small park, every hedge in the central reservation of every road, and saw not a thing. I began to wonder, did Mao wipe them out? But then yesterday, queuing to enter the Shanghai Expo world fair, I spotted a group of small birds hopping around the queuers' feet, and I made out the chocolate-brown caps, and there they were: tree sparrows.

So Mao didn't get them all; but his contempt for the natural world comprehensively wrecked much of China's environment. As for the birds, they are actually doing better in China now than they are in Britain, for intensive farming has reduced our own tree sparrow population by nearly 95 per cent. When you think about it, Mao didn't need millions of villagers banging pots and pans; he could simply have borrowed the Common Agricultural Policy of the European Union.

Yangtze clean-up has come too late for its river dolphin

While I have been here a huge clean-up has been announced of the Yangtze, China's greatest river which flows into the sea a few miles from Shanghai, and which is grossly polluted. Billions are to be spent on sewage treatment works and planting forests along the banks, which is tremendous news, but it will be too late for one creature: the baiji, the Yangtze river dolphin, which lives nowhere else. Or rather, lived. In recent years its numbers have plunged and it is now believed to have gone extinct; the Yangtze's pollution has done for it.

m.mccarthy@independent.co.uk

For further reading

'Mao's War Against Nature', by Judith Shapiro (Cambridge University Press, 2001)