Wild boars (Sus scrofa) are reputed fierce fighters. Males have long, sharp lower and upper canines used as strictly offensive weapons during intraspecific combat (Beuerle, 1975; Fraidrich, 1967). The risk of injury in these fights is higher than in most other ungulates whose horns, antlers or tusks can be used as shields against an opponent's weapons (Clutton-Brock, 1982; Geist, 1966a). This is true even of some Suidae, whose upper tusks are curved to the point of making them useless as offensive weapons (e.g., the warthog, Phacochoerus aethiopicus-Fridrich, 1967, and the babirusa, Babirousa babyrussa-MacKinnon, 1981). The fighting behavior of Sus scrofa, both wild and domesticated, is rather well known. Typically, two pigs about to fight approach each other frontally, up to a few meters. Then both face in the same direction for a parallel walk, sidling closer and closer. If neither gives up, they eventually contact to and continue walking, now pushing one another. One may then veer 180', re-establishing contact to resume pushing, but in a reverse-parallel position. During such shoulder (Beuerle, 1975), the animals circle rapidly and if both persist, they may start thrusting their heads and necks upwards and sideways with mouths open and tusks bared, both attempting simultaneously to hit and avoid being hit (Beuerle, 1975; Fraidrich, 1967; Signoret et al., 1975). This corresponds closely to observations I made on S. s. cristatus in Wilpattu National Park, Sri Lanka, from September 1972 to October 1973, and again from April to October 1983. I repeatedly observed, however, one element that seems to be missing from all published descriptions of the fighting behavior of Suidae. I call it wrestling: two pigs rear and lean against each other, with much grunting and frothing at the mouth (in adult males), as well as vigorous head jerks and foreleg flailing (Fig. 1). Each pig steps rapidly in place, apparently trying to maintain balance and to overthrow the other. Wrestling typically occurred at the end of a parallel walk when, instead of turning to reverse-parallel stemming, both animals went from parallel contact to rearing. Piglets occasionally went directly from a frontal approach, to rearing and wrestling. A wrestling match usually lasted a few seconds, but two adult males once stood continuously for 56 s. I observed 59 wrestling matches involving all age-sex classes, all were within classes (adult males: six, adult females: one, juveniles of both sexes: 11, and piglets: 41). I have corrected these absolute numbers to account for the frequency with which I sighted pigs of each class. To that effect, in 1972-73, I recorded the size and composition of all groups encountered. I used those values to compute the expected frequencies of wrestling used in the x2 tests. (For each class I excluded the cases where intra-class interactions could not occur.) Thus I used the following numbers of sightings-78 adult males, 1,022 adult females, 637 juveniles, and 467 piglets. Clearly, adult females wrestled less than expected by chance (x2 = 24.48, d.f. = 1, P 0.10). But adult males (x2 = 5.50, d.f. = 1, P < 0.025), and piglets (x2 = 62.72, d.f. = 1, P < 0.001) wrestled more than expected. Among adults, a match usually ended as soon as one combatant was overthrown once (X ? S.D. = 1.60 + 0.79 rears for seven matches), the winner pursuing the loser over a short distance. Among juveniles and piglets, however, combatants often reared again immediately after one was overthrown (3.10 ? 2.18 rears for 10 matches). Also, two juveniles or piglets often went from wrestling to reverse-parallel stemming and tusk fighting (even newborn piglets have tusks-Fraser, 1975). All fights and wrestling matches of piglets and most of the ones by juveniles were rather playful, typically interspersed with bouts of circular chasing and gamboling as their group left an open area around a water hole to return to the forest. On the contrary, wrestling between two adult males had nothing playful about it. This is consistent with the fact that adult males are much more solitary than the other classes, and seem quite intolerant of each other. Of the 378 adult males seen, 69.5% were solitary, whereas that proportion was less than 1% for the other classes. The latter were usually seen in groups (X ? S.D. = 9.70 ? 5.96, n = 237), and only 25.7% of the groups included adult males (one to three of them). Since all the wrestling matches observed involved two animals of the same class, combatants always February 1986 177
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Jun 1, 2006
Georgina M Jackson 
