Tapirs: North America’s Forgotten Megafauna

When one thinks of North America’s big, wild animals, one most likely thinks of the large animals of the American Wild West, such as bison and pronghorn, and the large predators such as cougars (Puma concolor), grizzly bears, and wolves. However, this thought process often leaves out the megafauna not ingrained into our culture. Jaguars are a prime example. While today they are often thought to be an exclusively tropical and subtropical animal restricted to dense rainforests, they are also a temperate species that in historical times inhabited much of the southern United States and southern South America, ranging as far north as Pennsylvania during the Pleistocene.[1] However, as humans have caused the range of jaguars to decrease, most people have forgotten that they are a native species, despite the fact that they are an integral and necessary component of nature.

A taxon that faces a similar issue is the tapir (Tapirus). While it may have a body resembling a pig and a snout resembling an elephant’s trunk, tapirs are members of the mammalian order Perissodactyla, and are most closely related to rhinoceroses and equines.[2] Often referred to as living fossils, tapirs are the most basal of living perissodactylids, having changed very little from their Eocene predecessors over fifty million years ago. Modern tapirs appeared in North America during the Oligocene,[3] and would later spread to Eurasia via the Bering land bridge, and to South America during the Great American Interchange[4] three million years ago.[5] Seven species of tapir inhabited North America during the Pleistocene, alongside a much more diverse variety of megafauna than are present today, including multiple species of proboscideans (elephants and their kin), giant ground sloths, saber toothed cats, and many more. At the end of the Pleistocene, however, most of these species disappeared. Some species, such as lions, horses, dholes (Cuon alpinus), and saiga antelope (Saiga tatarica) survived on other landmasses, while others, such as the mastodons or the glyptodons, became completely extinct. The cause for this large loss of megafauna has been debated, with some scientists claiming that a rapidly changing climate made it impossible for many species to survive. Other scientists support what is known as the Pleistocene overkill hypothesis, which suggests that newly arrived humans overhunted megafauna lacking adaptations against human hunting methods.[6] Support for the overkill hypothesis is seen with similar patterns in Australia and other isolated landmasses, including Madagascar and New Zealand, where megafaunal diversity collapsed shortly after the arrival of human. All species of North American tapirs became extinct during this extinction event except one, the Baird’s tapir (Tapirus bairdii).

A Baird’s tapir (Tapirus bairdii) in the wild.

Weighing up to 400 kilograms, the Baird’s tapir is the largest extant native animal in Central and South America, and the fourth largest animal in North America. The national animal of Belize, Baird’s tapirs are found primarily in the tropical rainforests of Central America, northern South America, and southern Mexico.[7] Tapirs are one of the few remaining large frugivores (fruit specializing herbivores) left in the Americas[8] and for this reason are considered keystone species, dispersing seeds for a wide variety of plants and consequently allowing the species that depend on those plants to flourish.[9] It is very likely that the ranges of many plant species shrank in response to the loss of tapirs in North America. Despite being such large animals, tapirs are solitary, elusive creatures that are rarely seen, even by the people who share their habitat. Despite this, tapirs have suffered from humans hunting for their prized meat and from rampant habitat loss as a result of agricultural development.

Baird’s tapirs are classified as endangered by the International Union for the Conservation of Nature, and among the North American megafauna, they are arguably the most threatened. There are only an estimated 5,000 to 6,000 individuals left in the wild.[10] A significant population of approximately 1,500 animals is believed to be living in Mexico, comprising the last population of tapirs in North America. The part of Mexico where they inhabit is part of the Neotropical ecozone that also comprises most of Central and South America. Northern Mexico and the rest of North America is part of the Nearctic ecozone, where many of the extinct American tapirs once inhabited. If Pleistocene rewilding were to ever take place in North America,[11] the extant tropical Baird’s tapir would likely prove a dismal candidate for resuming the ecological role of its extinct relatives, as a result of being poorly adapted to temperate climates. Instead, the mountain tapir (Tapirus Ppnchaque) would be better suited for this function as it is a temperate species.[12]

A captive mountain tapir. Could it replace its extinct North American relatives?

The plight of North American tapirs is representative of a larger issue of a shifting baseline in relation to wildlife, and what is considered to be natural or normal in a modern setting. Animals like bison, elk, sheep, wolves, and grizzly bears are all geologically (and evolutionary) recent arrivals to North America, while animals like tapirs, horses, pronghorn antelope,[13] llamas and camels are the original North American megafauna, along with several taxa that are now extinct (such as the gomphotheres, relatives to the elephant family). And yet, in a mere 10,000 years compared to millions of years of evolution on this continent, the feral horses now extant in North America are now believed by many people to be exotic, despite evidence supporting that some of the extinct equines of late-Pleistocene North America are synonymous with the Eurasian horse.[11, 14] That isn’t to say that species that are fairly recent in the fossil record are not native, but it does point out a certain stubbornness in people that believe that nature can only exist in the way that people remember it. For if a species can be persecuted or wiped out by humans, nature will bear the scars of its loss, but to humans, it is simply forgotten.

James Lee is a graduating high school senior. In the fall he will be attending SUNY College of Environmental Science and Forestry and majoring in wildlife science.

Notes

  1. Mark Gelbart, “How recently did the jaguar (Panthera onca) roam Eastern North America?GeorgiaBeforePeople.
  2. Perissodactyls,” American Museum of Natural History.
  3. The Oligocene was the third epoch of the Paleogene period, extending from 33.9 to 23 million years ago. See Polly PD, “The Oligocene Epoch,” University of California Museum of Paleontology.
  4. The Great American Interchange was the mass exchange of biota that occured upon linking of North and South America roughly 3 million years ago. See Larry G. Marshall, “Land Mammals of the Great American Interchange.”
  5. Marshall LG, et al., “Mammalian evolution and the great American interchange,” American Association for the Advancement of Science.
  6. What is the Overkill Hypothesis?” American Museum of Natural History.
  7. The World’s Tapirs—The Baird’s Tapir (Tapirus bairdii),” Tapir Specialist Group.
  8. Of the four (possibly five) living species of tapir, the Malayan tapir (Tapirus Indicus) is the only surviving species in the Old World, and is the largest species. See “The World’s Tapirs—The Malayan tapir (Tapirus indicus),” Tapir Specialist Group.
  9. Tapirs: Keystone Species for Conservation,” Lowland Tapir Conservation Initiative.
  10. Tapirus bairdii,” The IUCN Red List of Threatened Species.
  11. See “Interview with Dave Foreman,” The Wildernist. — Ed.
  12. Mountain Tapir,” EDGE.
  13. Pronghorn antelope are not closely related to the true antelopes of Eurasia and Africa, but are referred to as antelopes due to their similar morphology, which is a result of convergent evolution. “Animals of the Greater Yellowstone Region,” Greater Yellowstone Resource Guide.
  14. Orlando L, et al., “Ancient DNA Clarifies the Evolutionary History of American Late Pleistocene Equids,” Journal of Molecular Evolution.