Chapter 6: Sulawesi babirusa Babyrousa celebensis (Deninger, 1909)65
These can be categorised as ‘threat at a distance’, ‘surprise rush’,
‘nose in the air’, ‘head under jaws submission’, ‘front half sup-
ported’, and ‘boxing’ as the level of threat increased. The boxing
behaviour was the final stage observed, and this involved the two
adult males raising their forelimbs off the ground until both were
standing on their hind limbs facing one another (Figure 6.6A,B).
Once in this position the babirusa leaned and paddled
against the chest and shoulders of his opponent (Figure 6.6A).
Their snouts were held as high as possible (Figure 6.6B). If
one of the animals fell onto all four legs it reared up again and
the boxing continued. The boxing match usually lasted for
2–5 minutes, but could extend for up to 20 minutes. If the infe-
rior animal submitted at the earlier stage of ‘head under jaws
submission’ it would utter a very short squawk or a continu-
ous rattling stream of sound, the pitch and intensity of which
increased, as it seemed to perceive increased threat. Ironically,
the rounded upper canine teeth of the positionally and socially
inferior male appear to function as protection to the throat of
the superior male, preventing potential (accidental) damage
from the lower canines of the inferior animal (Macdonald et al.
1993; Leus et al. 1995). The teeth were never involved in ‘inter-
locked tooth’ wrestling matches (Blouch 1990; Macdonald et al.
1993; Patry et al. 1995). The relatively shallow tooth sockets sup-
porting the upper canines are not strong enough to withstand
such activity (Macdonald et al. 1993).
Female babirusa exhibit the ‘threat at a distance’ and ‘sur-
prise rush’ agonistic behaviours, although ‘nose in the air’ and
‘head under jaws submission’ were rarely seen between adult
females, and ‘front half supported’ and ‘boxing’ were never seen.
When two females confronted one another their behaviour was
often quite violent, fast-moving and noisy (Macdonald et al.
1993; Patry et al. 1995). The objective seemed to be to bite the leg
or foot of the opponent.Parasites and Diseases
Veterinary observations and autopsy reports from zoological
collections indicate that the morbidity and mortality of older
babirusa include several different tissue cancers. Little is knownTable 6.2 Numbers of groups of babirusa, according to the number of
adult males and females and the presence or absence of youngsters, seen
visiting salt-licks in North Sulawesi.
Adult males
0 1 2 3
Adult females
0 female only – 87 5 2
0 female + young – 6 0 0
1 female only 6 7 2 1
1 female + young 38 11 2 0
2 females only 3 0 0 0
2 females + young 13 7 4 0
3 females only 1 0 0 0
3 females + young 5 2 1 0
4 females only 0 0 0 0
4 females + young 0 1 0 0Table 6.1 The number of babirusa in each group (group size) and the
number of groups of this size seen visiting salt-licks in North Sulawesi.Group size Number of groups
1 104
2 27
3 35
4 20
5 15
6 12
7 7
8 6Figure 6.6 Two frames captured from
the early morning jousting bout between a
pair of young adult male babirusa brothers
in Surabaya zoo. (A) The ‘boxing’ agonistic
behaviour is demonstrated. (B) The winner
of this ‘boxing’ contest extended his nose
above the head of his opponent who was
already lowering his head below the chin of
the superior animal. Photographs by Alastair
A. Macdonald.Agonistic Behaviour
Studies of agonistic behaviour in zoological collections and in
the wild have shown that adult males progress through a reper-
toire of such behaviours (Macdonald et al. 1993; Leus et al. 1995).
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