The mysterious disappearance (and reappearance) of Latin America's white-lipped peccaries.

A study published in PLOS ONE documents the periodic disappearance (and reappearance) of white-lipped peccaries in nine South and Central American countries. According to the authors, the population fluctuations may be the first documented example of natural population cyclicity in a Neotropical mammal.

White-lipped pecaries. Credit: Jose Fragoso
White-lipped pecaries. Credit: Jose Fragoso

The study is led by the Universidade de Brasilia's Departamento de Zoologia and co-authored by more than 20 other organizations, including the Wildlife Conservation Society (WCS).

White-lipped peccaries (Tayassu pecari) are pig-like hoofed mammals native to Central and South American tropical forests. They form large herds of up to hundreds of animals and are extremely social. Researchers from Mexico to the Amazon have been intrigued by the sudden disappearance of large populations of white-lipped peccaries, as well as reports of previous disappearances and reappearances.

According to the study, disappearances represent seven-to-twelve-year troughs when peccaries vanish over 20-30-year population cycles. These can occur concurrently at regional and possibly continental spatial scales of 10,000-5 million square kilometers (3,861-1.9 million square miles).

The study suggests that mysterious disappearances may be caused by overpopulation, and crashes are likely facilitated by a variety of factors, including disease outbreaks, emphasizing the need for more long-term studies to better understand the causes.

The groundbreaking study incorporates 88 years of commercial and subsistence harvest data from the Amazon, as well as collaboration and detective work to document 43 different disappearances at 38 sites in nine countries. It confirms the existence of large-scale and long-term population cycles in this little-known species that is so ecologically important to neotropical forests, as well as culturally and socioeconomically important to the Indigenous Peoples and local communities who live in these forests.

From an ecological standpoint, the white-lipped peccaryis is regarded as a keystone species because it influences forest regeneration and plant populations, particularly palms, through seed predation, foraging, and leaf litter turnover. They are also regarded as ecological engineers because they maintain and expand forest mineral licks and wallows, which benefit a variety of other wildlife species. They are also the preferred prey of Latin America's apex predator, the jaguar (Panthera onca). Jaguar populations decline when peccaries become extinct.

From a socio-cultural standpoint, white-lipped peccaries are extremely important as a preferred subsistence hunting target for Indigenous Peoples and riverine and rural communities throughout their range. Many of Latin America's Indigenous Peoples' stories, oral histories, and art reflect this significance. In fact, some Indigenous Peoples have stories about peccaries disappearing and reappearing.

According to the study's lead author, Dr. Jose Fragoso of the Departamento de Zoologia, Universidade de Brasilia, Brasilia, DF, Brazil, the Instituto Nacional de Pesquisas da Amazonia (INPA/MCTIC), Manaus, Brazil, and the California Academy of Sciences, San Francisco, California, "this analysis highlights the importance of very large, continuous natural areas that enable source-sink population dynamics and ensure re

"It also emphasizes how working with indigenous peoples can aid in the resolution of biological mysteries. Our research also answers a critical question in tropical ecology: what happens to white-lipped peccaries when they die?"

Dr. Mariana Altricher, the senior author from the Environmental Studies Department at Prescott College in Arizona, believes that "This work sheds light on a long-standing mystery in tropical forests. It will help to direct future tropical research and conservation efforts. Most importantly, we must keep an eye on peccary populations, particularly in fragmented protected areas."

According to Dr. Harald Beck, Co-Chair of the IUCN Peccary Specialist Group and one of the study's authors, "This one-of-a-kind publication used historical and current data, as well as cutting-edge new modeling methods, to answer critical ecological questions about the spatial-temporal population fluctuations of the dominant Neotropical mammal, the white-lipped peccary. The paper will inform future Neotropical research as well as conservation efforts and policies."

"WCS remains committed to landscape-scale conservation at a series of Nature's Strongholds in Latin America, which is critical for wide-ranging species like the white-lipped peccary, especially given these population cycles," said Dr. Rob Wallace, Senior Conservation Scientist at WCS and one of the study's co-authors.

"Understanding these natural population cycles will be critical for interpreting our population monitoring efforts, which represent the gold standard for assessing our conservation impact, not just for white-lipped peccaries as a keystone species and socio-cultural touchstone, but also for the other wildlife with which they coexist—lowland tapir, collared peccaries, leaf litter biodiversity, a number of palm species, plant diversity, and, of course, the jaguar."

Journal name: PLoS ONE


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