When a British colonel called Jim Corbett was summoned to the thickly forested ravines of the Himalayas, he found people living in abject terror. Without guns, they were powerless to protect themselves from a small number of tigers that had developed a taste for human flesh. To live "and have one's being under the shadow of a man-eater" was not so different from prehistoric times, Corbett reflected, when early humans cowered in caves to escape the sabre-toothed tiger.

Corbett hunted alone. He tethered buffalo as bait, stalked silently in rubber-soled shoes and even tried to lure tigers by donning a sari and disguising himself as a woman cutting grass in the fields. Avoiding being dispatched by a tiger to what he called "the happy hunting grounds" in the sky, Corbett shot dead more than a dozen rogue tigers.

In the 70 years since Corbett bagged his last tiger, the balance of power between Panthera tigris and mankind has been dramatically reversed. In Corbett's day, 100,000 of these charismatic predators roamed free in Asia. As forests were slashed and hunting flourished, Corbett began to shoot tigers with film rather than with a rifle. "A tiger is a large-hearted gentleman with boundless courage and when he is exterminated – as exterminated he will be unless public opinion rallies to his support – India will be the poorer by having lost the finest of her fauna," he wrote presciently in 1944.

There are now just 3,200 tigers left in the wild. Three of the nine subspecies (the Bali, Javan and Caspian tigers) are extinct; a fourth, the South China, is also lost to the wild, with a few dozen specimens surviving in captivity. Tigers' survival is not guaranteed even in the most protected places: four died in a north Indian reserve named after Corbett earlier this year. The national animal of India, Nepal, Bangladesh, Malaysia and North and South Korea; the majestic creature at the heart of eastern and western culture from traditional Chinese myths to evil Shere Khan in the Jungle Book and cuddly Tigger in Winnie the Pooh; the big cat that sells us beer, petrol and other human essentials such as sugar-frosted breakfast cereal, is teetering on the very brink of extinction.

On 21 November, heads of state and senior diplomats from 11 key countries will gather in St Petersburg, the first time world leaders have met to discuss the fate of just one species. Backed by the World Bank, the Tiger summit is billed as the last chance to save the tiger. There are fears, however, it could prove as ineffectual as Copenhagen's climate change negotiations last year. The nation with the biggest tiger population, India, may refuse to send a high-level delegation; the Chinese, widely blamed for the tiger's decline, are still distrusted by environmentalists; even Russia, where Vladimir Putin has made tiger preservation a matter of personal pride, has suffered a disastrous loss of tigers in recent years. Some conservationists feel the participants are remote bureaucrats with no experience of the on-the-ground realities. Others are refusing to go at all.

Tiger experts are agreed on the prime, simple cause of its disappearance: it is being massacred for a lucrative illegal trade in traditional Chinese medicine. Shocking new figures released this week show that parts of between 1,069 and 1,220 tigers were seized between 2000 and April this year – an average of at least 104 animals per year. The vast majority of seizures of parts from illegally killed tigers, including skeletons, claws and skins, were in India, China and Nepal, according to Traffic, the wildlife trade monitoring network. "With parts of potentially more than 100 wild tigers actually seized each year, one can only speculate what the true numbers of animals are being plundered," says Pauline Verheij of Traffic and WWF. Between 2005 and 2008 it is estimated that 80% of western Nepal's tigers were killed by poachers. Tigers have also been snatched from supposedly well-protected reserves in India, and the decline of Russia's Siberian tiger in the last decade has been attributed to cuts in anti-poaching protection.

Tragically, each kill only increases the rarity – and price – of wild tigers. Despite the trade in parts and skins being banned by the UN Convention on International Trade in Endangered Species (Cites), Chinese communities across Asia still use tiger parts, including eyes and ears, in medicines and tonics. Rice wine made with tiger bones is sold as a health drink as an aid to cure arthritis and rheumatism, while tiger's penises are used in treatments for erectile dysfunction. Earlier this year, the Beijing-based World Federation of Chinese Medicine Societies explicitly ruled it was not necessary to use tiger parts. It was an important announcement, but the use of tigers in medicine has been illegal in China for 17 years and since then poaching has only escalated. While a 2007 survey found fewer than 3% of medicine shops and dealers in China claimed to stock tiger bone, there is clearly still a huge black market in China, Japan and South Korea, where, according to conservationists, a whole tiger can fetch more than $50,000 (£32,000).

Ten years ago, conservationists believed they had won their fight to save the tiger – habitats had been well protected by conservation efforts led by Indira Gandhi's government in the 1970s; in Russia, the Siberian tiger, all but wiped out in the 1930s, had recovered to 500 by the 1990s, helped by captive breeding programmes. Tigers are solitary, territorial predators that live at low densities and roam across vast tracts of land. Male Siberian tigers may patrol a territory of more than 300 square miles. To conserve them you need big spaces. The trouble is, you can't protect big spaces from poachers.

"We were pushing this idea of landscape conservation, which was too diffuse for the tigers," says John Robinson, an executive vice-president of the Wildlife Conservation Society. "I look at the things I was saying 10 years ago and I was wrong. I thought we'd done a pretty good job of protecting them in their core sites and we were looking to manage them in their wider landscape. We took our eyes off the ball and didn't see what was happening in the reserves. We didn't see that the uptake in poaching was as significant as it was."

Robinson is the lead author of "the 6% solution", a stark and grimly pragmatic new strategy set out in the journal PLoS Biology this autumn. He and other respected academics have identified 42 "source sites" (18 in India, with others in Sumatra and Russia's far east) that contain 70% of the remaining wild tigers. These sites make up just 6% of the tiger's current distribution and less than 0.5% of its historical range. Robinson argues that it is not possible to defend scattered populations of tigers from poachers. Instead, conservationists must save tigers in these source sites, from where upwards of 25 females can breed and, hopefully, then repopulate the wider landscape. "We really need to focus on these core populations. If we don't then we are going to lose them," he warns.

But conservationists do not all agree. WWF says landscape-scale projects must not be abandoned. Diane Walkington, head of species at WWF-UK, argues it is not enough simply to preserve core sites. She calls the PLoS Biology paper "a plan to help tigers not become extinct, but if you want tigers to recover you've got to look at corridors between areas, and if you don't establish these corridors now they will be gone for ever." She warns of a future where tigers will be confined to isolated reserves, little more than glorified safari parks, and wonders what happens when these reach their capacity in terms of tiger population. Corridors between areas need not be expensive reserves but could include hunting estates and farmed areas that allow tigers to roam in search of mates. Tigers are surprisingly resilient: recently one walked 120 miles through highly developed areas to find other tigers. But Walkington and Robinson agree on one thing: there must be a "sustained focus" on protection. "It's a bit like guarding the crown jewels. They never become unattractive to somebody. You never reach that point when you can say it's OK now."

Protection from poachers – even in reserves and national parks – is far from OK now, according to Bivash Pandav of WWF, who has spent four years visiting habitats in the 11 tiger-range countries. Speaking from his base in Kathmandu, he sounds close to despair. "The prime minister of India is very serious about tiger conservation but what is happening on the ground is completely different. A total lack of commitment is driving tigers out," he says. Reserve managers are not held accountable when a tiger is seized; junior staff, or even researchers are blamed. "The reserve managers should not only be sacked, they should be fined and put behind bars. Unless we give exemplary punishment to corrupt and irresponsible reserve managers, this trend of tiger decline will continue. [In] both the reserves in India, Sariska and Panna, where tigers have become extinct in the recent past, the managers have not only got off scot-free, rather, they have been promoted."

"We don't need rocket science to save tigers," continues Pandav. Tigers use fixed trails to patrol their favoured haunts. Conservationists set up cameras to capture tigers on these trails; poachers use leg-hole traps on the trails. "If you have a good knowledge of your reserve, if you monitor all the tiger trails on a weekly basis, you can minimise the poaching," he says. "In India the staff are not geared up to protect the areas from poaching. We need more foot soldiers. Poaching is carried out by organised gangs. You can control this only by having solid intelligence and then intelligence-driven patrolling." Armed patrols would help, he argues.

Tigers tend to attract alpha males as their champions: from Putin to the man behind the tiger summit, Robert Zoellick, president of the World Bank. These are characters whose pulses are unlikely to be set racing by trying to save a rare moth or a salt marsh. Dr Alan Rabinowitz, president and CEO of Panthera, is another rugged saviour of the tiger, dubbed "the Indiana Jones of Wildlife Conservation" by TIME Magazine. Rabinowitz, who recently helped identify previously undocumented tiger populations in Bhutan in the BBC's Lost Land of the Tiger, has incurable leukaemia. He likens current tiger conservation to someone telling a cancer patient they will buy them a new house. Like Pandav, he believes conservationists are not being held accountable for tiger losses. He cites an Indian reserve where tiger populations are thriving: it has a "shoot to kill" policy towards poachers. "I'm frustrated because the international conservation community is not pulling itself together. It's hiding behind trees," he says. "We know how to save tigers. It is not brain surgery. Tigers breed really well. Protect them, and they come back pretty quickly but none of the areas are being protected."

How much hope does he have for the tiger summit? "None," he says, "and that's why I'm not going." He calls it "a fiasco of more of the same" with a "preordained" agenda. Instead of focusing solely on the problem of poaching, Rabinowitz says the tiger summit is devoting too much time and resources to other issues, including educating local people about tigers and carbon emission allowances to preserve tiger habitat. "Money has not been focused on the one thing that will save tigers immediately, and that's adequate protection of the protected areas [from poachers]," he says. "I don't agree with the World Bank saying there are lots of pieces of the puzzle and we should fund carbon allowances and education and poverty alleviation – that's a huge distraction. It is just money for political correctness. We're giving money to stop the trade in China, stop captive breeding of tigers, help local communities. None of these things are helping tigers now. I don't give a damn how awful it is that the Chinese are breeding tigers. That's not our problem right now."

The authors of the "6% solution" calculate that just $35m (£22m) of additional investment per year would be enough to protect the 42 key sites and thus stop tigers being made extinct. "Not a lot of money to do something that is culturally pretty important for the planet," points out Robinson. In fact, it's the equivalent of Wayne Rooney's salary for just two seasons. Although Robinson does not expect to see "a lot of people signing cheques" at the tiger summit, he remains cautiously optimistic. "I also believe that this is the last and best chance for the international community to come together and contribute to tiger conservation."

Ahead of the summit, the Chinese government has retreated from suggesting it might favour legalising the trade in farmed tiger products, which conservationists fear would only legitimise and fuel further demand for wild tiger parts. Walkington hopes that everyone will commit to doubling tiger numbers by the next Chinese year of the tiger – 2020 – and agree real details on how to implement a tiger recovery programme. "We've seen the Chinese government showing a much more positive focus on tiger conservation," she says. Convincing the Chinese to reduce the demand for tiger parts in traditional medicine would be a good outcome, according to Pandav. "But unless conservationists set their own house in order, protecting reserves on the ground, no amount of summits or conferences or debates are going to save the tiger," he warns.

For Rabinowitz, a tiger "is the epitome of the wild and wildness. It's kind of a cliche, but we need wild in our lives. The tiger is a piece of that wild. We lose that and it's the cork out of the bottle – everything else spills out. If we can't pull together enough to save what is the most iconic living species, then what are we going to do for lesser species?"

Jim Corbett vividly described how he tracked down the Mohan man-eater despite being afflicted with a cough (bad news for silent stalking). Watching flattened blades of grass spring up, a sign the tiger had been there only moments before, he eventually spied a spot of gold – the tip of the tiger's tale protruding from behind a rock. Fearing it was ready to pounce, he found it fast asleep. "I do not know how the close proximity of a tiger reacts on others, but me it always leaves with a breathless feeling – due possibly as much to fear as to excitement – and a desire for a little rest," he wrote, after shooting it.

If only we could give the tiger some respite too.