Peaceable Peccaries 
Much snuggling and nuzzling enable these relatives of wild pigs 
to maintain cooperative and cohesive herds 
by John A. Byers 
In 1683, an anatomical account of 
a New World mammal was published 
in the Philosophical Transactions of 
the Royal Society of London. The 
beast had been brought alive to Eng- 
land and when it died was given to 
Dr. Edward Tyson for examination 
and dissection. Tyson had in hand a 
male of a species known today as the 
collared peccary, Tayassu tajacu. His 
wonderfully descriptive name for the 
animal was the Mexico musk-hog. 
Spanish explorers of the time also 
knew the animal and referred to it 
as the javelina (from the Spanish 
jabalina, or “spear,” a reference to 
the animal’s large canine teeth). 
The collared peccary is one of three 
extant species in the family Tayas- 
suidae. The tayassuids diverged from 
the true pigs, or Suidae, in the early 
Oligocene, about 40 million years ago, 
and differ from true pigs in several 
important respects. Like pigs, how- 
ever, peccaries possess a tough, disk- 
shaped snout and have a proclivity 
to root. Although they were once cos- 
mopolitan, peccaries are confined to- 
day to the New World. The collared 
peccary occurs over a huge range be- 
tween Argentina and the American 
Southwest; its close relatives, the 
white-lipped peccary and the chacoan 
peccary, are found only in the tropics 
and subtropics. In the United States, 
collared peccaries occur in the south- 
ern regions of Texas, New Mexico, 
and Arizona. 
Peccaries and pigs differ in many 
ways. To begin with, the former are 
much smaller: collared peccaries are 
about three feet in length, stand about 
a foot and a half at the shoulder, and 
weigh about fifty pounds; wild boars 
(from which domestic pigs were de- 
rived) may weigh up to ten times as 
much. The coats of peccaries are com- 
posed entirely of large, coarse bristles; 
those of pigs vary, but in general they 
have hair as well as bristles, the latter 
being more scattered, shorter, and less 
robust than the bristles of peccaries. 
Pigs have a simple stomach; peccaries 
have a multichambered stomach re- 
sembling that of the ruminants in form 
and, somewhat, in function. Pigs have 
rather primitive feet; peccaries have 
more specialized feet that show ad- 
aptations for running. The canine 
teeth of pigs curve outward, as in the 
wart hog; those of peccaries are 
straight and interlocking. Finally, the 
two groups differ with respect to litter 
size and social organization. Pigs give 
birth to large litters of small, relatively 
helpless young; mothers spend much 
time alone caring for their young in 
a nest or den; and there are no per- 
manent social groups. Peccaries do 
have permanent social groups and fe- 
males bear litters of only two young, 
which are able to walk soon after birth. 
As a result, mothers are able to rejoin 
their herd quickly. 
I studied peccaries on the 3-Bar 
Wildlife Area, a sixty-square-mile re- 
search preserve maintained by the Ar- 
izona Department of Game and Fish. 
I was drawn to the collared peccary 
because, in the literature, there were 
tantalizing intimations that the species 
was highly social. A major goal of 
my earlier research had been to dis- 
cover whether specific types of early 
experience lead to specific types of 
adult behavior in animals. More gen- 
erally, what developmental strategies 
does each species use to achieve its 
level of social organization? This is, 
of course, a huge question, and one 
way to begin attacking it is to look 
for broad patterns at the ends of the 
spectrum of social organization, that 
is, in highly social and in nonsocial 
species. My intimations that peccaries 
would be at the high end of the spec- 
trum turned out to be correct. 
The social unit of peccaries is a 
cohesive herd, composed of equal 
numbers of males and females. This 
reflects a sex ratio at birth of 1:1 and 
the fact that individuals rarely disperse 
into new areas. Herd size in the Ameri- 
can Southwest, and throughout Central 
America and South America, in those 
areas where reliable counts have been 
made, averages twelve to fifteen mem- 
bers. There is essentially no sexual 
dimorphism. Within herds, animals re- 
main close to each other, and indi- 
viduals become visibly upset and may 
utter loud, squalling cries if they lose 
contact with their fellows. Herds 
therefore act as a unit in which all 
individuals move, feed, and rest to- 
gether. 
Each herd occupies an exclusive 
home range about one square mile 
in size. Within each home range a 
network of peccary trails connects 
feeding locations and traditional rest- 
ing sites, or bed-grounds. The animals 
give the strong impression that they 
possess a detailed “cognitive map” of 
the home range: when undisturbed, 
their movements are deliberate, and 
they choose energetically efficient 
paths (by angling up a hill rather than 
attacking it head-on or by contour- 
Lyle K. Sowls 
