Prioritizing species protection to prevent extinction and zoonotic spillover


By Kristen Pope

At markets around the world, wildlife are stacked in cages, alive and waiting to be sold. A crate with primates might be on top of an enclosure containing civet cats or bats, with another container of rodents below. All the while, tens if not hundreds of market visitors pass by. As the animals—often immunosuppressed due to stress—face crowded conditions and drop urine and feces into the pens below, it creates a perfect recipe for zoonotic spillover.

The global wildlife trade is valued at $12-23 billion U.S. dollars, and tens of millions of wild animals are hunted and traded each year. Some are eaten locally for subsistence, while others are sold around the globe as luxury food items, for traditional medicine, or research.

Sulawesi flying fox, Scott Heinrichs

While many think of the wildlife trade as illegal and underground, much of it is out in the open, though there are many gray areas. Not much data are available on the illicit aspects of the wildlife trade, since it is often associated with other forms of trafficking, including arms, drugs, and even humans.

However, more is known about the legal wildlife trade, and one 2020 study published in Global Ecology and Conservation found that 73% of markets and supermarkets in North Sulawesi, Indonesia sold wildlife meat, including flying foxes, wild pigs, snakes, and other animals. The authors estimated between 660,000 and one million flying foxes alone were being traded each year, which they found unsustainable.

Scientists are concerned the wildlife trade could lead to the extinction of species through overexploitation, but they also have another concern: zoonotic spillover. When humans and wildlife are in close contact, pathogens could pass between them, leading to the spread of disease.

Since resources to address issues in the wildlife trade are limited, BCI Research Scientist Dr. Luz de Wit and colleagues examined ways to use existing resources most efficiently to prevent extinctions and lower the risk of zoonotic spillover. In their 2022 paper in Conservation Science and Practice, de Wit and her co-authors analyzed 1,161 terrestrial mammals and developed the “conservation and health trade risk” (CHT) index to help prioritize the monitoring and regulation of traded species with high risk of extinction and high zoonotic potential. They identified 284 priority species, and this list includes  primates, even-toed ungulates, rodents, carnivores, and bats.

Mariana flying fox. Yushi & Keiko Osawa

Around 30 bat species were identified as priority species, including the Endangered Mariana fruit bat (Pteropus mariannus), which is considered a delicacy in the Mariana Islands, as well as the gray flying fox (Pteropus griseus), which is classified as Vulnerable by the IUCN and traded in North Sulawesi’s wild meat markets as both food and traditional medicine for asthma. Around 80% of the priority bat species are eaten by humans, and 16% are traded internationally as luxury food items.

Banning or regulating the wildlife trade through a “top down” approach may be ineffective and unfair, especially since some communities rely on trading wild animals for their income,  or consuming wild meat for subsistence. In contrast,working with communities who depend on the wildlife trade  to find other ways to make a living, as well as alternate food sources, such as domestic animals, in addition to educating community members about public health risks, is a promising way to concentrate efforts for the best results for humans and wildlife.