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Captive birds for sale in a cage at a bird market in Hong Kong. A team of scientists has developed a technique that can determine whether such birds were raised in captivity or captured from the wild. Photo: AFP via Getty Images

New method to combat illegal wildlife trade reveals whether animals were raised in captivity or captured from the wild

  • University of Hong Kong scientists can now tell whether songbirds for sale at markets were wild-caught by the molecular fingerprint on their flesh and feathers
  • Other projects include mapping global pangolin trading routes, an app that recognises endangered fish, and using drain water to identify species in wet markets

Dr Caroline Dingle is used to the sight of terrified songbirds for sale in Hong Kong markets, and it’s clear which ones are not used to being in captivity.

“They bang themselves on the sides of the cage trying to get out,” says the evolutionary ecologist and head of the Conservation Forensics Laboratory at the University of Hong Kong (HKU).

“On any given day there are about 1,000 exotic birds for sale as pets [in the city]”, she adds, and the trade is “quickly emptying the forests of Southeast Asia of songbirds”.

Most of this trade in Hong Kong is above board, but the sale of certain wild-caught bird species is illegal or requires permits. To skirt the rules, however, some vendors pass off wild-caught birds as captive-bred. To tackle this problem, Dingle’s forensics lab is developing ways to determine the origins of individual birds and help identify those traders who break the law.

A recently arrived shipment of song birds from Africa at the Yuan Po Street Bird Market. Photo: Caroline Dingle
The illegal wildlife trade has been in the spotlight lately because of its link to the coronavirus pandemic, which is suspected to have originated in bats and possibly reached humans via pangolins, the world’s most trafficked wild animal.

Hong Kong is a global hub for the illegal wildlife trade. More than 15,000 tonnes (16,500 short tons) of plant and animal products have been smuggled through the city in the past five years, according to “Trading in Extinction – The Dark Side of Hong Kong’s Wildlife Trade”, a 2019 report by the philanthropic ADM Capital Foundation.

This staggering total includes parts and products from more than 3,000 elephants, 50,000 pangolins and almost 200 rhinos, and thousands of acres of tropical forests destroyed for hardwoods, the report says. The remainder comprises live creatures – tens of thousands of songbirds, tropical fish, turtles and snakes.

A frozen pangolin seized in Hong Kong. Pangolins are the world’s most trafficked wild animal. Photo: Kadoorie Farm and Botanic Garden

It is difficult to prove a wildlife crime because smugglers, traders and producers can camouflage the origin of their cargos, disguise endangered species as legally tradeable ones, “launder” animals that require permits, and mislabel manufactured products. But Dingle and other scientists at the Conservation Forensics Laboratory have combined their individual areas of expertise to create methods and tools that can be used by the authorities to unravel this complex web.

Although a bird’s terrified behaviour in a cage does not prove it came from the wild, a technique known as “stable isotope analysis” can help scientists prove a bird’s provenance through the molecular fingerprint left by its diet on its flesh and feathers.

Infographic: China’s wildlife trade

Isotopes are different varieties of the same chemical element. Nitrogen, for instance, in one type of food has a specific amount of certain nitrogen isotopes, and a regular diet of this food will leave a particular isotopic signature in the body of the animal.

Modern techniques can measure these isotope signatures to determine an animal’s dietary history. Two individuals of the same species – one living in the wild, the other raised in captivity – will have very different isotope signatures in their bodies.

“In the wild, parrots mostly eat fruit and their isotope signature reflects that,” Dingle says. “But in captivity they are fed pellets that have wheat and corn that give a very different signature.”

The current coronavirus pandemic crisis should serve as a wake-up call. It highlighted the importance of curtailing the illegal trade of wildlife like never before
David Baker, professor of ecology and evolutionary biology, Conservation Forensics Laboratory

Scientists at the laboratory are now building up a database of isotope signatures of commonly traded bird species. Once the testing procedure is robust enough, authorities would only have to provide a single feather from a confiscated bird for isotope analysis to prove it had been caught in the wild.

The lab has a wide range of projects under way. These include the molecular tagging of endangered trees in Hong Kong to prevent them from being harvested and smuggled out; and using network analysis to map global pangolin trading routes to enable the authorities to disrupt the trade.

“I see our role as trying to identify the emerging issues,” says David Baker, a professor of ecology and evolutionary biology at the lab. “One such issue is mislabelling, especially in processed foods – we are eating things that we are told are something else,” he says, such as endangered eels commonly being sold on supermarket shelves.

“This is extremely important as it involves every consumer in the market. I don’t think anybody knows how much is mislabelled. It is a huge problem.”

A toucan pokes his beak between cage bars at the Yuen Po Street Bird Market in this photo from 2013. Photo: AFP via Getty Images

Professor Yvonne Sadovy, another member of the Conservation Forensics Lab and an expert on reef fish and fisheries, has been focusing on the trade in Napoleon wrasse, a coral reef fish prized as a delicacy. Overfishing has caused populations to plummet.

In Hong Kong, traders must have a permit for each legally imported Napoleon wrasse, which can cost as much as US$850 per serving. One year, Sadovy’s team counted about 1,000 of these large fish in local restaurants even though no fish had been legally imported that year.

“One vendor showed an old permit from several years before and said ‘it’s the same fish’, which it could not be because they only stay a few weeks in the tanks,” Sadovy says.

Yvonne Sadovy in French Polynesia with an adult Napoleon wrasse. Photo: George Mitcheson

Facial recognition technology and machine learning have been adopted to combat the “laundering” of the wrasse, preventing the use of a single permit for different fish.

Napoleon wrasse have intricate, individual tattoo-like patterns on their faces. An app is being developed that will enable anyone seeing a wrasse in a restaurant to take a photo and upload it, together with the location, to a website. Software will then run the fish’s facial pattern against those of legally imported wrasses. If there is no match, the fish is an illegal import.

A Napoleon wrasse in a tank at a restaurant in Sai Kung in Hong Kong. Photo: Stan Shea
Hong Kong has one of the highest seafood consumption rates in the world – more than 70kg (154lb) per person per year, according to the WWF. Much of it is wild-caught and then sold in wet markets. Johnny Richards, a molecular biologist with the Conservation Forensics Laboratory, has been developing a toolkit that will allow the authorities to monitor these markets for the presence of endangered species.

Richards developed a methodology to extract environmental DNA, also known as eDNA, of various species from drain water. Investigators can simply scoop up 50ml (1.7 fl oz) of water from a drain flowing out of a market and send it to the lab to be analysed for the DNA of various fish species.

In a pilot study last year, drain water from three Hong Kong wet markets was found to include the DNA of two species of thresher shark and a black-chinned guitarfish. The wild populations of all three have been decimated by the shark-fin trade and dealing in these species in Hong Kong requires permits.

“If this intelligence highlights a chronic presence of species that are not supposed to be there, then the government might take further action,” Baker says.

Fish for sale at a wet market. Photo: Johnny Richards

Despite the potential, the Conservation Forensics Laboratory does not plan to commercialise the tool kits and expertise, but instead intends to provide the service to society for free, both in Hong Kong and beyond.

“My personal preference is that we make these things freely available because many of the people who are affected the most are the ones that cannot afford the technology,” Baker says. “To expect a payment from a developing country for a problem that they did not cause in the first place … this just seems very wrong to me.”

Baker is confident that stronger conservation forensics capabilities will be a deterrent to smugglers and traders. “They already want to know what we are up to,” he says. “At our international workshops there are a few shady characters who come in, sit at the front. Nobody knows who they are. They take pictures of every slide, every single person.”

Indonesian fishermen unload various catches of fish that includes sharks and baby sharks at a fish market. Photo: AFP via Getty Images

Baker says the laboratory needs to reach out to potential industry patrons, organisations and individuals. He believes passionate environmentalists will see the lab’s efforts as important conservation work and a way to improve the reputation of both Hong Kong and mainland China in the conservation field.

“The current coronavirus pandemic crisis should serve as a wake-up call,” he adds. “It highlighted the importance of curtailing the illegal trade of wildlife like never before. And Hong Kong is well-positioned to develop solutions of biosecurity through scientific study.”

This article appeared in the South China Morning Post print edition as: The caged bird sings