Part II: Species Accounts128
Reproduction and Growth
Reproduction
Bushpigs generally breed once a year or twice in three years
depending on body condition. In southern Cape forests,
bushpigs of the plateau zone (lower-lying indigenous forests
adjoining agricultural land) were in better condition (higher
body mass at age, higher body mass to size ratio, higher serum
haemoglobin and packed cell volume levels) than those of the
foothill zone (indigenous forest, pine plantations and fynbos
shrublands). Higher fecundity levels (mean live births per
female per annum) were evident in bushpigs inhabiting the
plateau zone (Seydack 1990). In southern Africa farrowing has
been reported to mainly occur between October and January
(Thomas & Kolbe 1942; Sowls & Phelps 1968); peaking during
spring (September–November). Bushpig neonates are relatively
small and when born at the beginning of the warmer spring/
summer season, the associated lower thermal stress would
favour the growth and survival of juveniles. Furthermore, veg-
etative growth in spring (herbage intake: Table 12.3) would be
expected to result in increased availability of digestible protein
and phosphorus, meeting the elevated demands of lactation
(Seydack 1990).
The percentage crude fibre of pregnant female ingesta (24.5)
was found to be higher than that of lactating (16.4) or non-
reproductive (17.5) individuals. Such a diet of pregnant females
facilitates lower metabolic rates and higher rates of digestive
efficiencies favouring energy storage, making provision for high
energy costs during lactation. On the other hand, the diets of lac-
tating females had higher levels of percentage ash, phosphorus
and calcium than pregnant or non-reproductive females, facili-
tating high rates of milk production. The energy costs of lactation
were substantial, with bone marrow fat percentages < 1.5 months
post-partum in comparison with those ≥ 1.5 months post-par-
tum of 82.0 and 38.7 per cent, respectively. Both duration of lac-
tation and litter size affected maternal condition. The product of
these two parameters was inversely related to maternal condition
(Seydack 1990). Disproportionately few pregnant females had
bone marrow percentages below 70 per cent. Very low levels were
associated with starvation (0.7 per cent), socio-spatial conflict
such as territorial encroachment in females (0–33.2 per cent) or
lactation (9.9–21.4 per cent). Most adult bushpigs which had less
than 60 per cent bone marrow fat were solitary (Seydack 1990).
Males may reach physiological sexual maturity as early as
16–20 months of age (Sowls & Phelps 1968; Seydack 1990).
Earliest conception has been recorded in females between 7
and 22 months of age. However, due to factors relating to socio-
spatial status and body condition (nutrition), successful breed-
ing may only occur much later. Reported litter sizes vary from 1
to 8; most commonly between 3 and 4, but rarely exceeding 6, the
number of mammae (Sowls & Phelps 1968; Skinner et al. 1976).
Gestation lasts about 17 weeks (just over four months) and
neonates weigh between 600 and 1000 g (Sowls & Phelps 1968;
Seydack 1990). Lactation may last between 4.0 and 5.5 months
(Seydack 1990). Breeding is restricted to females pair-bonded to
males (monogamy) and territorial status. The ages of such femalesranged between 3.0 and 11.6 years (mean: 8.1 years; n = 14),
whereas the ages of sexually mature non-breeding females
ranged between 3.3 and 6.5 years (mean: 4.2 years; n = 7).Growth
In southern Cape forests, asymptotic body mass was found to be
71.9 and 67.9 kg for males and females, respectively. Just over 50
per cent and 80 per cent of asymptotic body mass was attained
at one and two years of age, respectively. Final body mass was
reached between 2 and 5 years of age. The average growth rate
of free-ranging juvenile bushpigs was 100 g/day and of captives
126 g/day, of similar magnitude as recorded by Sowls and Phelps
(1968). The average yearling (1–2 years) growth rate was about
half of that of juveniles. Bushpig yearlings in the foothill zone
were of below-average size relative to their ages in comparison
with those from the plateau zone (Seydack 1990).Behaviour
Social and Socio-spatial Organization
The family group, consisting of the territorial pair and one or
two generations of offspring, represents the core of bushpig
sociality. There is typically only one adult female per family
group as part of the monogamous, territorial pair. Four socio-
spatial classes can be identified: territorial male/female pairs
with or without progeny, solitary male individuals occupy-
ing non-exclusive home ranges, dispersing yearling/subadult
individuals, and nomadic adults. Mean group sizes of between
2.2 (southern Cape: largest group observed: 10) and 3.0 indi-
viduals (eastern Cape) were reported by Seydack (1990: South
Africa); 2.6 (6) by Breytenbach (1977: South Africa) and 3.2
(11) by Ghiglieri et al. (1982: Uganda). Large aggregations, such
as those reported in Kingdon (1979), were attributed to obser-
vations of temporary aggregations of more than one sounder
(Attwell & Bearder 1976; Breytenbach 1977). Well-studied suid
species such as the European wild boar (Beuerle 1975), the
warthog (Frädrich 1974; Mason 1982) and the giant forest hog
(d’Huart 1978) were found to be non-territorial. Breytenbach
(1977) suspected the bushpig to be territorial. He observed
bushpigs to move within well-defined areas and only when a
large or special food resource became available did more than
one sounder occur in the same area (Breytenbach 1979). A clear
socio-spatial pattern of resource territoriality was confirmed
and described for the bushpig in the forests and thickets of the
southern and eastern Cape (South Africa) by Seydack (1990).
As demonstrated in southern Cape forests, spatial exclusivity
was a prominent feature of ranging relations between bushpig
individuals (Seydack 1990). Territorial pair-bonded bushpig
females were intolerant not only towards other adult females but
also towards intruding subadult and subdominant males. This
year-round maintenance of spatial exclusivity is interpreted to
represent resource-based territoriality, as opposed to the typi-
cal bovid male mating territoriality. Resource group territo-
riality was maintained through spatially related high levels of
aggression, notably between females, male dominance status,
patrolling and marking behaviour. Fatal aggressive encounters.01412:38:17