The Co-Existence of Feral Hogs and Peccaries in the Americas

An old episode of Anthony Bourdain’s No Reservations sparked my interest in Brazil’s Pantanal region.  Bourdain searched eastern Brazil in vain for a rare species of fish he wanted to eat.  He was told it was still abundant in a remote part of western Brazil, so he purchased a charter flight to take him there and satisfy his culinary curiosity. The pilot flew the small aircraft through storms, and Bourdain and his crew weren’t sure they were going to make it.  Then, after arrival, Bourdain suffered the worst back pain he’d ever felt, and his producer fell ill with a tropical fever.  Nevertheless, they continued filming and I was impressed with the quantity and quality of wildlife.  It reminded me of 18th century descriptions of Kentucky and early 19th century accounts of Oklahoma.  On a boardwalk through a jungle Bourdain saw a red monkey that no one could identify.  Though there are riverine forests, most of the Pantanal consists of vast treeless plains, variously flooded here and there.  The indigenous people who sparsely populate the Pantanal use it as pastureland, and large herds of feral hogs and peccaries intermingle with cattle.  Caimans and capybaras abound in the flooded parts, and huge flocks of wading birds crowd the water holes.  Incidentally, Bourdain did get to sample the fish.

Map of Brazil’s pantanal.

The Brazilian Panatanal is 1 of the richest wildernesses left on earth.  It encompasses 75,000 square miles and includes at least 12 different types of ecosystems.  463 species of birds, 209 species of fish, and 236 species of mammals live in the region.  It has the healthiest population of jaguars in the world.  Peccaries and wild pigs are the most common ungulates.

Feral hog and vultures feeding upon a dead cow in Brazil’s pantanal region.

Collared peccary.

White lipped peccaries.

Peccaries and pigs are superficially similar in appearance, but they are separated by over 25 million years of evolution.  There are 2 species of peccaries native to the Pantanal–the aggressive white-lipped (Tayassu pecari) and the collared (Pecari tajacu).  Feral hogs (Sus scrofa) are not native to the Pantanal and were introduced hundreds of years ago.  Scientists who study the interrelationships between peccaries and pigs expect the latter to be detrimental to the former, but their studies find this is not true.  A recent study examined the consumption of 37 plant foods among the 3 species, and they found minimal dietary overlap.  Feral hogs favored grugru palm nuts (Acrocomia aculeata), collared peccaries preferred bay cedar (Guazuma sp.), and white-lipped peccaries liked the fruit of a plant in the coffee family (Alibertia sessilis).  All 3 species did feed upon the fruit of Astralea phaleratata, a type of palm.  Palm nuts taste coconut-like.  There was more overlap in diet between white-lipped peccaries and wild hogs than between collared peccaries and wild hogs.  Collared peccaries foraged at times when they could avoid pigs and white-lipped peccaries.

Chart showing diet overlap between the 3 species.  From the below referenced paper.

Palm nuts from the grugru palm are the favorite food of feral hogs in the Pantanal.

Alibertia sessilis fruit ( relative of coffee)  is the favorite food of the white-lipped peccary in this region.

The study determined bay cedar was the favorite food of the collared peccary.

During the Pleistocene new species of mammals periodically crossed the Bering Land Bridge and invaded the Americas, and vice versa.  Like pigs and peccaries, many of the co-existed.  Deer, bear, and big cats came from Eurasia.  Horses and camels went from the Americas to Eurasia.  Co-existence was not always permanent.  Felids from Eurasia outcompeted many species of canids, a group of carnivores originating in North America.  Deer from Eurasia outlasted 3-toed American horses.  The composition of mammals on both continents changed over time, and co-existence between species can be temporary or long lasting.

Reference:

Galetti, M. ; et al

“Diet Overlap and Foraging Activity Between Feral Pigs and Native Peccaries in the Pantanal”

PLOS ONE 2015

 

Pleistocene Georgia’s Javelinas

Hernando De Soto brought the first pigs (Sus scrofa)  to Georgia in 1540, releasing them in the wild where they could feed on the mast and provide a ready food source.  He also offered them as gifts to Indians on a line from the southwestern corner of the state to the area of what’s now Augusta.  Diseases from pigs, such as influenza and trichinosis, may have wiped out many Indian tribes.  Feral pigs from hunters introducing wild boars and escaped farm-raised individuals interbred and now are overrunning much of Georgia.

Map from the Georgia Department of Natural Resources

Feral hogs

This is evidence that an ecological niche for a pig-like animal still exists in Georgia, and it suggests that some time late in the Pleistocene, Indians must have overhunted peccaries into extinction.  Otherwise, they would still be here because feral hogs sure thrive in state today.

Georgia’s Pleistocene Peccaries

Illustration of long-nosed peccary (top) is from the Illinois State Museum.  The replica of the flat-headed peccary (bottom) is from the Cincinnati Museum.

There were at least three kinds of peccaries (or javelinas) living in what’s now Georgia during the Pleistocene.  By far, the most common species was the long-nosed peccary (Mylohyus nasatus).  Fossils of this animal have been excavated in Bartow County from three different caves and from the Isle of Hope site along the coast.  In Georgia fossil specimens of Mylohyus are almost as common as those of white-tail deer and in fossil sites from south Florida and Arkansas it even outnumbers deer.  They inhabited forested areas, feeding on acorns, roots, and other forest mast.  They probably fed on deer fawns and turkey eggs, like modern feral hogs do.  It exhibited an odd body shape for a pig-like animal, resembling a deer more than a javelina.

A second species of peccary from Georgia’s Pleistocene was the flat-headed kind (Platygonus compressus).  Shaped more like what would expect of a javelina, it preferred dry brushy habitat, similar to that inhabited by a closely related extant species, the Chacoan peccary (Catygonus wagneri), now found in a small area along the border of Paraguay, Bolivia, and Argentina.  Flat-headed peccaries occupied Georgia’s sandhills and dry forests, habitat which expanded during the frequent dry climate cycles that struck the southeast during the Ice Age.  Though far less common here than the long-nosed peccary, their fossils are consistently found in Georgia, South Carolina, and Florida fossil sites.

A third, still extant species, the collared peccary (Pecari tajacu) probably lived in south Georgia during warm climate phases.  Their fossils are exceedingly rare in Florida’s abundant sites and are associated with species of mammals that required frost-free climate, such as Eremotherium and glyptodonts.  Only three sites in Florida yielded remains of this species, including one in the Suwanee River only about 50 miles from the Georgia border.  During warm interglacials collared peccaries expanded their range throughout the south but were never as common as the other two.

Why do feral hogs thrive now where Pleistocene peccaries became extinct?

The answer is simple: litter size.  Collared peccaries have only 1-4 young.  Until protected by game laws, they were in danger of extinction in some regions.  Chacoan peccaries have an average of 2.4 young per litter.  Pleistocene peccaries probably had the same small litter sizes.  By contrast, feral hogs can have up to 13 piglets in a litter.  Wild boars evolved on the same continent as man.  To survive human hunting pressure, individuals that produced greater young had a better chance of passing on their genes–a kind of evolutionary selection.  Moreover, after humans domesticated pigs, for obvious economic reasons, we artificially selected individuals that produced more young–in a way, creating a Frankenstein-like monster.  Once they escaped back into the wild, wild hogs were able to overcome human hunting pressure by reproducing rapidly.

The differences between true pigs and peccaries.

This is from the National Park Service site devoted to Big Bend National Park where a good population of collared peccaries lives.

……………………Peccaries…………………………..Pigs…………………………………..

Has 3 toes on hind foot……………………………..Has 4 toes on hind foot……….

bones fused in the foot………………………………Bones in foot not fused……….

lower arm bones are fused…………………………lower arm bones not fused….

38 teeth………………………………………………….34-44 teeth………………………

canine teeth are straight……………………………canine teeth are curved………

have scent glands……………………………………..lack scent glands………………

have a complex stomach……………………………have a simple stomach………

lack a gall bladder……………………………………..have a gall bladder……………

have a short tail…………………………………………have a long tail………………..

lack sweat glands………………………………………..have sweat glands…………..

References

Hulbert, Richard C.; Gary Morgan and Andrea Kervin

“Collared Peccary (Mammalia, Artidodactyla, Tayassuidae, Pecari) from the late Pleistocene of Florida”

Museum of Northern Arizona Bulletin 65

www.nps.gov/bibe/naturescience/javelina.htm

www.wildlifemanagementinfo/files/wild_hogs_4.pdf

Yahnke, Christopher; et. al.

“The Specific Fecundity, litter size, and sex ration in the Chacoan Peccary (Catagonus wagneri)”

Zoobiology  16: 301-307 1997