Pangolins are thought to have passed the coronavirus to humans, after they first caught it from horseshoe bats
Before researchers suggested pangolins may be a missing link in the transmission of coronavirus from bats to humans, most people had never even heard of them. Yet these scaly, ant-eating mammals are smuggled in huge numbers to Asia and are in danger of extinction.
There are eight species of pangolin, split evenly between Africa and Asia, and each one of them is barred from international trade. So identifying confiscated scales and body parts as “pangolin” can be enough to prosecute a criminal case. But discerning different species and tracing their geographic origins is more tricky. This is where wildlife forensics comes in, a rapidly developing field that uses scientific procedures to investigate crimes against wildlife. To help crack down on intricate trafficking routes and poaching hotspots, scientists and laboratory technicians are figuring out ways to analyse the DNA and dietary history of seized animals and their products.
Pangolin scales are a booming business in Asia thanks to their status as an ingredient in traditional Chinese medicine, while the animal’s meat is considered a delicacy
Most consumers come from mainland China and Vietnam, where pangolin meat is a prized delicacy and keratin scales are a popular ingredient in traditional Chinese medicine, touted as a cure for anything from asthma to cancer, and as an aid to help mothers with lactation. Pangolins have recently been in the spotlight for their potential role in the Covid-19 pandemic. Sars-Cov-2, the virus that causes the novel disease, is suspected to have originated in horseshoe bats and possibly leaped to humans via pangolins.
Because the four Asian species have been hunted to near extinction, criminal networks are extending to Africa. In 2019 alone, authorities seized 81 tonnes of pangolins scales, with more than half of shipments coming from Nigeria. Traffickers frequently change their routes, however, which makes tracing a shipment’s origins extremely difficult, according to a report by the wildlife trade monitoring group TRAFFIC.
Forensic techniques, such as DNA analysis and radiocarbon dating, as well as sniffer dogs, are already being used to tackle the illicit trade in timber, rhino horn and elephant ivory. The analysis of DNA can also help identify a pangolin species from confiscated scales. “Seizing tonnes of pangolin scales that arrive in Hong Kong or Kuala Lumpur is great, but you can only really prosecute people on the ground, and you don’t know where these scales are coming from,” says Rob Ogden, programme director at TRACE, an NGO that brings together forensic scientists and law enforcement agencies around the world. For instance, the distribution of the ground pangolin (Smutsia temminckii) stretches from Southern Africa through East Africa and as far as Sudan and Chad.
These are just a few bags of scales from poached pangolins; in 2019, a massive 81 tonnes of scales were seized – and that is only the illegal shipments that were intercepted, so the real number is likely far higher
To tackle this problem, researchers at the University of Hong Kong (HKU) are developing new ways to determine the origins of birds, turtles – and most recently, pangolins – based on what they ate. Different food sources have different ratios of stable isotopes, or atoms of the same element (e.g. oxygen, carbon and nitrogen) with slightly different weights, that are stored in animal tissue. Water and soil also vary in their isotope ratios according to geography, which allows scientists to create an “isoscape” for specific regions or locations that can be matched with that found in pangolin scales.
Caroline Dingle, an evolutionary ecologist in HKU’s conservation forensics lab, explains that stable isotope analysis could be used to study whether animals are predominantly poached in a single country and shipped directly to Hong Kong, or whether they are hunted across the African continent and consolidated in a transit hub like Nigeria. “That information can be used to help understand where you need to send enforcement,” she says.
There is one major drawback, though. The isoscapes will vary across the range of a pangolin species, but unless forensic scientists have access to a database showing how they change between, say, South Africa and Sudan, it will be difficult to pin down where an individual animal was caught.
Fortunately, ecologists have started compiling these isoscapes on the ground by collecting large numbers of water, soil and plant samples. It’s a seemingly herculean task for the immense areas of land on the African continent. “There’s a huge amount of work to do to create an isoscape for any species found across such wide ranges as pangolins,” says Ogden.
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