Whether it is clearing out Siem Reap's floating zoos, exposing Phnom Penh restaurants, or conducting a raid near Cambodia's often porous borders, the image of the government's Wilderness Protection Mobile Unit [WPMU] stirs the imagination.

Set up in July 2001 as a special unit dedicated to fighting wildlife trade in Cambodia, the WPMU is a joint venture between the Department of Forestry and Wildlife, the Royal Gendarmerie, and San Francisco-based NGO WildAid.

Its aim is to infiltrate and obliterate the illegal wildlife trade in Cambodia, a daunting task given the size of the problem.

The world-wide wildlife trade is worth an estimated US$9 billion a year. It involves the capture of thousands of animals, destined to become food or medicines, or to supply the exotic pet market.

Cambodia, with its relatively large proportion of forest cover, has some of the world's most sought-after species, and is a major source for the wildlife trade.

In its first 18 months the WPMU caught 239 traders, rescued over 10,000 wild animals, confiscated 1.3 tons of fresh meat, and two tons of dried wildlife parts.

These statistics suggest the immensity of the trade. Yet trying to quantify the extent of the problem is difficult.

"One of the main problems with wildlife trade in Cambodia is that accurate wildlife population surveys are not yet sufficient," says WildAid deputy country coordinator Delphine Vann Roe. "Therefore estimating the damage that the wildlife trade is doing to such populations is a shot in the dark."

One of the main culprits for the existence of the trade is a herbal encyclopedia of Chinese medicine composed over four centuries ago. It lists animals that are reputed to have therapeutic properties, among them species native to Cambodia such as the tiger and the pangolin.

Most of Phnom Penh's notorious bush-meat restaurants have been closed down, but WildAid operations coordinator Nick Marx says battling traditional attitudes is harder.

"Wildlife has been a commodity for ever," Marx says. "It won't get stopped until there is action by respective governments, along with adequate support from the West."

Marx's role is to coordinate the work of the WPMU with the Phnom Tamao rescue center - Cambodia's only major rescue facility.

Set within 2,500 hectares of secondary growth forest, of which 1,200 hectares are part of the park, Phnom Tamao's main aim is to rehabilitate wildlife into its natural environment. It is also the final home for many animals unable to be returned to the wild because of their injuries.

In the quarantine section the more humbling side of animal rescue shows its face. Cages holding pileated and yellow-cheeked gibbons and other species fill the area. Endangered wildlife is alive and well here, but only thanks to the work of the WPMU.

"Everything here is eaten in one form or another," Marx said. "Gibbons are monogamous, and what probably happens is that the parents are killed, and the young are sold as pets."

"Many Asians have eaten all their own wild life, so now they are set on decimating the rest of the world too," Marx said.

The desire to eat exotic animals is rooted deep in many Asian cultures; it shows one's social status. And the reason for the prolific trade in Cambodia is simple: money talks. In China, pangolin meat can command a street price of over US$100 a kilogram, an attractive option for many faced with poverty.

"There are tendencies to see wildlife as a thing of power. It costs money to buy these animals, and rich people in many Asian countries consume wildlife at parties, or for medicinal purposes," Roe says.

"The proof that it still exists is that animals continue to disappear every day. We believe [though cannot prove] that the wildlife trade has strong links with human and drug trafficking."

According to Roe, traders are adept at changing tactics to avoid detection and have been skilled at taking their trade underground. They have been known to swap cars to evade authorities and have employed decoys in their efforts to get away. All this makes the original successes of the mobile unit more difficult to sustain.

"We are finding that we have to rely on a strong informant network, which we are in the process of building, and information from the public to find traders," Roe says.

"It is a difficult job as the threat to our informants is real; if they are identified their lives could be in danger."

Cambodia has some lax laws when it comes to trapping wildlife. It is not illegal to own or to set a snare in Cambodia. It only becomes illegal when an animal is captured by one. The law seems weighted in the poacher's favor.

WildAid hopes to find funding for an additional mobile unit to increase surveillance throughout Cambodia in the near future, and the world at large is waking up to extent of the wildlife trade.

In May ASEAN agreed to a five-year plan to combat the trade, seen as a threat to Southeast Asia's bio-diversity, and scares such as bird flu and SARS have shown how infection can jump the species barrier, adding fresh impetus to efforts to stop the trade.

But until there is real change in traditions and appetites, the existence of units such as the WPMU are Cambodian wildlife's best hope of survival.