A major centre of this insidious trade is India, where traders operate out of the bazaars below the Red Fort in Old Delhi. The bazaar is an entrepot for the trade in all sorts of seriously endangered species. Tiger skins, especially, are hot property.
In Delhi a well-cured skin will fetch 100,000 rupees, about pounds 1,360. In Europe or Japan a good skin might fetch pounds 8,000. A 15kg tiger skeleton would fetch pounds 7,500 and, once ground down into powder for medicine - used in oriental medicine as a treatment for rheumatoid arthritis - the value per kilo in Hong Kong, Tokyo or the Chinese communities of the US or Europe is 30 times the Delhi price.
India is proud of its Royal Bengal tigers, and there are local organisations that pursue illegal traders, with limited success. Although attempts to fight back against this trade are fraught with danger, there are those who have dedicated their lives to preventing the extinction of endangered species throughout the sub-continent.
Belinda Wright and Ashok Kumar, of the Wildlife Preservation Society of India, have gained legendary status in the fight against the illegal animal trade. Ms Wright, born and brought up in India, has photographed, filmed and saved tigers since childhood; Mr Kumar is a former business manager turned wildlife sleuth. Together they have carried out more than 180 operations against wildlife traders, with the stings frequently resulting in shoot-outs.
I came across this determined pair while filming for the BBC, following a team of investigators working for the charity, Care For The Wild. "Debbie" and "Chris", from the UK-based charity, and an Indian translator called Rohan had made contact with a group of traders in tiger skins, operating out of the basement of a Delhi bazaar.
During the encounter the traders, Moushim and his wife, Laxhmi, were talking of an immediate trade in 10 skins and promising more. Demand expressed in Delhi means more dead tigers supplied from the foothills of the Himalayas, the forests of Madhya Pradesh or the mangrove swamps along the Bangladesh border. To prevent the deaths of more animals, it was vital that the sting took place within days: here the experience of Belinda and Ashok would be invaluable.
A deal was arranged in my hotel room in central Delhi. The dealers arrived, sat by the swimming pool, offered a range of rare animals and departed, promising to return. When they did, both were arrested. A victory, but sadly it took 24 hours before the Delhi Wildlife Warden's investigators arrived to search the traders' warehouse. When they arrived, all the skins had been removed, along with hundreds of protected birds kept in a dark basement.
Moushim and Laxhmi are now on bail. Belinda and Ashok are optimistic that they will eventually go to jail - Moushim is wanted on 13 other wildlife offences. Judging by past experience, though, justice might not be done. Out of Belinda and Ashok's 180 cases they have obtained only one conviction. "Indian wildlife law is improving," they say optimistically. It has to, radically, if the tiger is to be saved.
`Chasing The Tiger' will be screened on BBC1 at 10pm on Tuesday, 6 April.