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Big Cats and Big Risks – Will Failure to Protect the Tiger’s Rainforest Domain Lead to More Disease Spillover?

April 2, 2021

Joe Figel is a Fulbright Scholar to Indonesia where he is working to help protect Sumatran tigers from poachers. He is also an adjunct faculty member in the Department of Life, Ocean, & General Sciences at Highline College. Joe is a 2020 recipient of the Asian and Global Studies Course Development Grant, administered by the Henry M. Jackson School of International Studies at the University of Washington. This award gave him the opportunity to develop a new module for ENVS 103 at Highline – Illegal Wildlife Trade: Implications for Human and Environmental Health.

Amid the incessant shuffle of news on the social, economic, and health-related consequences of COVID-19, coverage about the pandemic’s environmental impacts has been comparatively scant. Even rarer is exposure documenting the effects of COVID-19 on wildlife populations. This oversight is significant because environmental degradation is one of the main contributors to the emergence of infectious diseases, of which more than 60% are zoonotic – they originate in animals, usually wildlife. Paradoxically, populations of tigers – whose intact habitats represent buffers against future disease outbreaks – are among the conservation-dependent species likely to suffer the most from lockdowns and pandemic-associated funding shortfalls.

Infectious disease spillover occurs most frequently in the tropics where, compared to temperate regions, pathogen diversity is significantly greater. Despite covering less than 10% of Earth’s land surface, tropical rainforests support at least two-thirds of our planet’s biodiversity, a substantial portion of which is comprised of microscopic pathogens

At the opposite end of the food chain are tigers, which have considerable top-down influence on prey behavior and ecosystem functioning in the world’s 3rd-largest rainforest. Roaming across hundreds or even thousands of square miles, tigers have the largest home ranges among sympatric mammals in the rainforests of Southeast Asia. But widespread habitat loss and rampant poaching have drastically diminished the important ecological roles of these apex predators. About 95% of the tiger’s historic range is gone, seized by humans for infrastructure development and perpetually expanding agriculture. Most tiger populations now persist in patches of neglected habitat too rugged, swampy, or otherwise inconvenient and undesirable for human development.

For decades, accumulating evidence has revealed the links between human exploitation of tropical forests, ecological degradation, and subsequent risks of zoonoses. Habitat loss and fragmentation leads to more frequent contact between humans and infected animals. In degraded landscapes, humans further introduce an array of disturbances that severely disrupt integral ecosystem processes, setting the stage for potentially contagious interactions between wildlife, domestic animals, and humans. As one recent example among many, forest fragmentation amplifies the risk of tigers contracting the highly contagious canine distemper virus.  

Figure 1. A sun bear confiscated from poachers by environmental authorities in northern Sumatra.

Figure 1. A sun bear confiscated from poachers by environmental authorities in northern Sumatra. © Joe Figel, Fulbright, and Universitas Syiah Kuala.

Two of the more urgent threats, however, are increased poaching and hunting. Unsustainable commercial wildlife harvest reaches its apogee in Southeast Asia where the outbreak has emboldened opportunistic poachers. Behind the veil of lockdowns, trappers and middlemen have been granted cover for their illicit activities (Figure 1). Depleted anti-poaching patrols combined with persistent trafficking of wildlife parts does not bode well for the conservation of high-demand threatened species, which are increasingly dependent on vigilance and strict protection from poachers. In an unsettling twist of irony, tiger parts were recently marketed by Vietnamese traffickers as an (unproven) treatment for COVID-19

Besides poaching, tigers and their prey face heightened pressures as cash-strapped individuals in many rural communities have increasingly turned to subsistence hunting. Forest-edge villagers and other rural peoples employed in the informal sector (e.g. as farmers or street vendors) already live on the edge during pandemic-free times; they simply do not have the resources to weather the storm of paralyzing lockdowns. In the absence of stimulus checks, many marginalized communities become heavily reliant on forest products during times of economic downturn. Hunting spikes, attributable to economic disruptions caused by COVID-19, have occurred in some of Southeast Asia’s most biodiverse forests

Government agencies now struggle to strategize plans for safeguarding protected areas at a time when even their own antipoaching staff are susceptible to movement restrictions caused by lockdowns and funding shortages. If poachers ignore wildlife laws, there is little reason to believe they would obey stay-at-home orders, especially when their ‘home’ is a makeshift poaching camp in the forest. (At disturbing frequencies, Vietnamese poachers are taking extended trips into the forests of neighboring Southeast Asian countries to poach tigers and their prey). 

Despite the indispensable services provided by tropical ecosystems, humans have plundered, and we continue to plunder, the last intact rainforests, depleting tiger populations and increasing our exposure to pathogens and zoonotic disease reservoirs. In Bangladesh and Malaysia, where the status of tigers is especially precarious, bats disrupted by habitat loss often roost in domestic fruit orchards amidst factory farms and human settlements. Domestic pigs that forage on fallen fruit contaminated with bat excrement can become infected with Nipah virus which they subsequently transmit to pig farmers who recently experienced  devastating mortality rates as high as 91 percent.

Figure 2. A wild, 3-legged Sumatran tiger that somehow managed to escape from a snare trap.

Figure 2. A wild, 3-legged Sumatran tiger that somehow managed to escape from a snare trap. © Joe Figel, Fulbright, and Universitas Syiah Kuala.

Our roads exacerbate the impacts of habitat fragmentation and expediate the spread of invasive species while massive agricultural operations introduce domesticated animals, replacing wild herbivores with livestock. We set snares that maim, cripple, and kill critically endangered tigers (Figure 2) and further imperil rapidly declining populations of leopards and their prey. 

Figure 3. My study area landscape in northern Sumatra. © Joe Figel, Fulbright, and Universitas Syiah Kuala.

The cases outlined here highlight the urgency to recognize the contributions of intact tropical  forests (Figure 3) for prevention of zoonotic diseases, which are driven by land-use change and agricultural expansion. Globalization can facilitate the spread of a virus from a seemingly remote wildlife market as fast as an outbound international flight. The world now understands the gravity of pandemics; nobody needs convincing that an infectious virus could kill many millions of people or bring the global economy to a standstill. What is apparently less understood is the importance of nature-based solutions for avoiding future disease outbreaks. We need more preventative measures, not reactive ones. Preserving tropical forests should be low-hanging fruit for spillover prevention and global climate change mitigation. Strategies that protect, manage, and restore natural or modified ecosystems are low-cost and readily available today. 

The commonly expressed COVID-19 rallying cry, “We are in this together” needs to reflect upon and redefine the “we.” Indeed, the pandemic provides a valuable lesson for humanity to better understand the fragile interconnectedness of environmental, human, and wildlife health. Our ability to adapt and fundamentally adjust our relationship with natural ecosystems and their non-human inhabitants will have considerable implications for environmental health, endangered species, and, quite possibly, the future of life on Earth.