Chapter 9: Common warthog Phacochoerus africanus (Gmelin, 1788)93
at 36–48 months. Adult weight fluctuates strongly with season,
with the male losing up to 20 per cent of weight through the mat-
ing season and following dry season. In southern Africa, adult
male testes mass increases fourfold during the March–May mat-
ing season (Mason 1985, 1986; Cumming 2013).
Mother and offspring form a strong social unit until the next
birth season. The bond between mother and female offspring
lasts through breeding cycles, while the bond between mother
and male offspring lasts about 1 year, when males leave the
sounder. Both sexes show a high degree of philopatry (Cumming
1975; Somers et al. 1994; White 2010).
Prenatal mortality is about 9–17 per cent (Child et al. 1968;
Mason 1982). Piglets are vulnerable to cold, malnutrition, drown-
ing, infanticide, and predation (Somers et al. 1995; Figure 9.4).
Piglet and juvenile (i.e. first year) mortality often is >50 per cent,
and can reach 90 per cent during severe droughts (Sowls & Phelps
1966; Bradley 1968; Cumming 1975; Rodgers 1984; Mason 1990).
Populations sometimes decline >50 per cent/year (Mason 1990),
but may grow >60 per cent/year where large predators are absent
(Somers & Penzhorn 1992; Swanepoel et al. 2016).
Maximum age in the wild is 17 years (Spinage 1972; Mason
1984), but few reach 12 years (Cumming 2013). Maximum age
in captivity is 18.6 years (Smith 2011). Mean longevity in the
wild is given as about 2.6 years by Spinage (1972) and as about
3.5–4.0 years by Bigourdan (1948). Interbreeding with other
suids has not been reported.
Behaviour
Three main social structures exist for P. a f r i c a n u s: matriarchal
sounders (= family groups), bachelor sounders, and solitary
males. Matriarchal sounders are comprised of an adult female
with her latest litter, sometimes with one or two female offspring
from a previous litter. Two or more independent but related
sounders that share food, water, and burrows form a ‘clan’. Mean
clan size in southern Africa is about 18 individuals. Although
the home ranges of sounders within a clan may overlap consid-
erably, contact among sounders is infrequent. Clan home ranges
in southern Africa are about 0.9–3.5 km^2 (Cumming 1975, 2013;
White & Cameron 2009; White 2010).
The mean size of sounders varies among sites and with time
of year, but usually falls within the range 2.0–3.6 individuals.
Note that solitary individuals, which are generally common,
are considered ‘sounders’ and are typically included in calcula-
tions of sounder size, including means and ranges. Sounder size
ranges 1–12, including 1–4 adults. The largest sounder reported
comprised 16 individuals. The larger sounders are matriarchal
sounders. Bachelor sounders typically comprise 2–4 males.
Yearlings are rarely solitary. Large sounders usually fragment
in the dry season, or before/during the birth season. Higher
resource availability appears to be related to higher sounder
size (Cumming 1975; White 2010). In north-west Zimbabwe,
27 per cent of encounters were with solitary adults (19 per cent
males; 8 per cent females), 20 per cent with bachelor sounders,
5 per cent with all female sounders, 6 per cent with yearling
sounders, 40 per cent with matriarchal sounders, and 3 per
cent others (Cumming 1975). In central Namibia, 46 per cent
of encounters were with solitary animals (Cunningham 2016).
In north-east South Africa, 49 per cent of sounders consisted
of at least two adult females (Somers et al. 1995). See table 5 at
http://www.wildsolutions.nl/phacochoerus/.
Phacochoerus africanus and P. aethiopicus are unique
among cetartiodactyls in that they rely on burrows for shelter
from predators, heat and cold. Although P. a f r i c a n u s some-
times excavate burrows (Clough 1969), it is far more common
for them to modify existing holes, digging and removing soilFigure 9.4 Adult female lion Panthera
leo with a freshly killed juvenile
common warthog Phacochoerus
africanus at Meru National Park, central
Kenya. Photograph by Yvonne de Jong
and Tom Butynski..01112:33:32