Deforestation could pose disease threat to Amazon’s white-lipped peccaries

by Sean Mowbray 

  • White-lipped peccaries are vital ecosystem engineers and an important source of food for people living in the Amazon.
  • Deforestation has reduced their habitat and, in addition, researchers highlight that disease is an understudied factor in their conservation.
  • Scientists say it could represent an additional threat to an already vulnerable species, as continuing deforestation and expanding agricultural frontiers can bring greater contact between domestic animals and wildlife, potentially leading to spillover events.

Ongoing deforestation of the Amazon Rainforest jeopardizes multiple species, such as the white-lipped peccary (Tayassu pecari). It can also increase the risk of other threats like disease, potentially including spillover events from domestic animals. How this is impacting the species remains broadly unknown and understudied, according to a recent paper published in the journal Biological Conservation.

Researchers point to two main questions: how diseases influence local and cyclical disappearances of peccary populations and how introduced diseases might impact the species more broadly, a problem potentially exacerbated by deforestation.

White-lipped peccaries undergo regular boom and bust cycles, recurring over two decades or more. Researchers say these disappearances are natural and that the species may exhaust available resources before eventually succumbing to disease. White-lipped peccaries are listed as vulnerable to extinction by the IUCN, ​​the world conservation authority, and at the national level in Brazil.

In the recent paper, scientists reviewed past research on disease in white-lipped peccaries and found that significant knowledge gaps exist. “Infectious diseases are probably involved in the emergence of repeated local episodes of disappearance of [white-lipped peccary] populations in the Amazon region,” the authors wrote. “However, the impact of infectious diseases on the decline of peccary populations has not yet been evaluated.”

A herd of white-lipped peccaries.
Research shows that white-lipped peccaries undergo natural boom-and-bust cycles over large areas of their range. Disease could play a role, say scientists, as the species exhausts natural resources, becoming more susceptible to viruses and pathogens. In this sense, it may be the “final step” in completing the cycle, says Pedro Major at the Barcelona Autonomous University, who was part of a team that reviewed scientific studies on disease in wild peccaries. Photo courtesy of FundAmazonia.

How much introduced diseases influence these boom-and-bust cycles is unclear, Pedro Mayor, a researcher at Barcelona Autonomous University and an author of the study, told Mongabay in an interview. In the Amazon region, domestic animals are concentrated mainly around forest edges, yet the disappearances occur within the rainforest, he said. “There doesn’t seem to be a relation between production animals and these wild populations. But the problem is that there are so few studies on diseases on white-lipped peccaries and wild populations,” he continued.

Meanwhile, however, deforestation and hunting can leave populations more vulnerable, Maria Fernanda Menajovsky, a researcher at the Barcelona Autonomous University and lead author on the paper, told Mongabay in an interview. “Pathogens that are usually in the populations may become more dangerous under these circumstances.”

From the limited studies conducted, some “important diseases” have been found in wild peccaries, such as those that can cause high death rates, particularly in young animals, Menajovsky added. She pointed out that antibodies of Aujeszky’s disease, also known as pseudorabies, were found in wild peccaries. But these were limited both geographically and in sample size. In short, it remains unknown how extensive any crossover is or where potential risk hotspots may exist.

For Harald Beck, co-chair of the IUCN Peccary Specialist Group, who was not involved in the study, the hypothesis that these natural disappearances involve diseases is a solid one, but details are currently lacking. A separate question raised by the paper, he stated, was whether and to what extent introduced diseases may be impacting populations more broadly. “Is it possible that some of those diseases are spreading from livestock? Can it be that some pigs that are not indigenous bring in some diseases?” he told Mongabay via a video call.

Deforestation and agriculture.
Introduced diseases and potential spillover from domestic animals is another concern for the species as deforestation and the advance of animal agriculture increases possible points of interaction where the spread of diseases may occur, say researchers. Limited studies have identified some potentially concerning diseases but their extent and impact on populations is unknown. Photo courtesy of CIFOR via Flickr (CC BY-NC-ND 2.0).

An ecosystem engineer under threat

White-lipped peccaries are pig-like animals that roam in herds of up to and more than 100. They are an important source of protein for Indigenous populations and their ecological role is equally vital. As “ecosystem engineers,” the species helps maintain the ecosystems in which they live, said Beck.

For instance, they regulate the growth of certain plant species and provide habitat and drinking water for multiple species when they create muddy wallows. “They’re creating breeding ground and foraging habitat for many amphibians and many other animals,” Beck said. Their eating habits, consuming species such as palms, also help to shape forest environments.

Peccaries require large tracts of land to roam and forage. With habitat loss, expanding farmland, and hunting comes the possibility for disease to spread between domestic animals and wildlife, researchers say. Parceling out habitat into smaller areas can cut populations off from one another, while diseases can potentially spread quickly amongst these herd animals as they are highly social, regularly interacting by rubbing their snouts on one another, Beck said.

Across their wide range, white-lipped peccaries have already lost much of their habitat and are now extant in only around 21% of the species’ historical range, according to the IUCN Red List. A study published in 2020 estimated that the species’ range in Mesoamerica has been reduced by as much as 87%. Populations in the Amazon, however, are more stable yet still face risks from ongoing loss of their habitat.

Joares May Júnior, a wildlife pathologist with the Federal University of Rio Grande do Sul, stated that possible points of interaction between peccaries and domestic animals are important to consider when assessing the risk of disease. “All these animals look for salt in the wild,” he told Mongabay by phone. “The salt is a point between wild animals and domestic animals to have interactions, so this is one step.”

Wallows act as habitat and water sources for a wide variety of species.
White-lipped peccaries are important ecosystem engineers and play a vital role in maintaining forests by foraging and creating wallows, which act as habitat and water sources for a wide variety of species, explains Beck. Photo courtesy of Harald Beck.

Other possible interaction points can happen via hunting or white-lipped peccaries leaving forested areas to raid crops. A previous study showed that wild peccaries’ and feral pigs’ foraging habits overlap in Brazil’s Pantanal region. “All these kinds of interaction, all this overlap, increases the risk to exchange parasites or to exchange viruses. That’s the kind of interaction we have in Brazil,” added May Júnior, who was not involved in the study.

For him, the research was important as it highlighted that the exchange of disease can occur at multiple levels. Importantly, continued deforestation and agricultural expansion can amplify this risk.

More broadly, wildlife disease is considered an understudied and persistent threat to multiple species in tropical regions, such as Brazil and elsewhere around the world, potentially impacting some of the world’s most endangered species to an as yet unknown degree.

To address existing knowledge gaps, the study authors called for more expansive research efforts to assess the current disease situation facing white-lipped peccaries, involving the collaboration of local people. Studies on infectious diseases in captive peccaries and domestic pigs in the Amazon region could also provide insights into “potential emerging pathogens,” they stated.

Beck agreed that such investigations were necessary to inform any potential conservation action to protect this culturally and ecologically important species. “If you’re able to preserve [peccaries] and preserve the habitat, you preserve many other endangered species, from amphibians to birds to primates,” he said. “A healthy peccary population also means a healthy forest community overall.”

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