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Chapter 22: Pygmy hog Porcula salvania (Hodgson, 1847)termite mounds in their area of activity. They also ingest earth
while foraging. Analysis of the dried stomach contents of an
adult hog killed in Barnadi in April 1977 revealed that ingested
material comprised a large proportion of soil particles, in addi-
tion to fibrous plant material and insect exoskeletal material,
mostly ant heads (Oliver 1980). The nutritional requirements
of captive animals can be met by feeding them on a balanced
diet of a large variety of tubers, cereals, pulses, fruits, vegetables,
and eggs, while encouraging them to forage in paddocks with
natural vegetation and plenty of soil invertebrates such as earth-
worms, termites, ants, and beetles.
Reproduction and Growth
The differences in the size of social groups may be due to the
species’ strongly seasonal reproductive pattern. Adult males
evidently join oestrous females during the rutting season, and
are disruptive to existing group composition by ousting other
males. Even in captive conditions adult males, which are main-
tained together peacefully, became mutually intolerant and very
aggressive in the rutting season. Threat displays in these animals
are similar to those in wild pigs (Sus spp.). Fighting ensues if
intimidation fails, but often weaker males squeal and run away
if threatened. The onset of parturition finally disrupts the exist-
ing sounder composition and pregnant females separate from
the young of the previous season, moving away from her social
group and making a new nest on her own to farrow.
Practically all information available on the reproduction of
pygmy hogs originates from captive animals. These data, sup-
ported by incidental observations from the wild, indicate that
the mating usually takes place between December and March.
The mating and maternal behaviour is also similar to that of
wild pig (Sus spp.). The length of the oestrus cycle is around
21 days, but oestrus itself lasts only three to four days. Most pre-
vious reports suggest that gestation lasts 120 ± 5 days (Mallinson
1977; Oliver 1980; Narayan et al. 1999a); however, recent obser-
vations while monitoring faecal hormones in captivity indicate
that it could be as high as150 days, but this needs further inves-
tigation. Farrowing usually takes place between late April and
early July, which also happens to be the most favourable period
for parturition in the wild as this coincides with the regrowth of
vegetation following the early rains at the end of the dry season.
The infants are therefore comparatively well developed before
the heavy monsoon rains start.
Litter size is usually four to five (average 4.7), but in captivity
it could be as large as eight or as small as two. Large litters of six
or seven often have a runt, but these also occur occasionally in
smaller litters (Narayan et al. 1999a). The eyes of the newborn are
open and they are believed to suckle within a few hours of their
birth, and sows normally lie down in the nest to nurse. Postnatal
sows remain with their litters and emerge only occasionally and
for short periods to forage or defecate. Piglets do not emerge
from the nest until the fifth or sixth day, and then only for brief
periods at first, staying very close to and behind their mothers.
The young hogs almost double their weight every three weeks
or so during the first couple of months, and reach adult (female)
weights and size in eight to nine months. Although the hogs
become sexually active at nine months or less in captivity, this
is probably due to the better diet in captivity and may not be the
case in the wild. The females take about 20 months and the males
2–3 years to display sexual maturity.Behaviour
Pygmy hogs are extremely shy and secretive in the wild. Because
they remain hidden in tall dense grass and rarely emerge into
the open, very few observations exist in the wild. Most refer to
sounders of four to six, and rarely, groups of eight to 10 indi-
viduals, usually adults accompanying young. Observations in
captivity, particularly in very large enclosures with simulated
natural habitat, indicate that the focus of these social units is
often an adult female, accompanied by the young of the previ-
ous season. These groups are cohesive, and asocial with other
groups. The overall movements of foraging individuals and
groups often appear haphazard, but individuals maintain con-
tact in their dense habitat by ‘soft grunting’ vocalizations. Pairs
are seen infrequently, mostly in the mating season. Most sight-
ings of solitary animals are of adult males.
Nest building: pygmy hog is the only suid and one of the few
mammals of the world who build and use nests at all times of the
year, and not just for farrowing as prevalent among most other
suids. These nests are built by all age-/sex-classes. Each social
group, or solitary individuals, make one, and rarely two, nests
for everyday use.
The nests are primarily made from the leaves of thatch
grasses and the hogs show a special preference to species such
as Narenga porphyrocoma, Imperata cylindrica or Saccharum
spontaneum. They are constructed over a slight (c.5 cm) depres-
sion on the ground in the midst of very thick vegetation and
measure about 110–125 cm in length, 60–90 cm in width and
about 15–20 cm in height (aboveground). The hogs place small
bunches of the thatch grass in a cross-wise pattern to make or
repair a nest. The nests are constructed so well that the central
chamber remains dry even after heavy rains. The entire social
group rests and sleeps together in an active nest, and rarely some
groups use a second nest in the same area for the purpose.Parasites and Diseases
The pygmy hog sucking louse (Haematopinus oliveri) is a spe-
cies-specific ectoparasite found only on the pygmy hog Porcula
salvania (Mishra & Singh 1978). The parasite has been recorded
on wild-caught hogs (Oliver et al. 1997) as well as on captive
hogs (Narayan et al. 1999b). Four gastrointestinal nematodes
(Ascarops strongylina, Ascarops dentate, Globocephalus urosubu-
latus, and Capillaria species) have also been recorded from cap-
tive hog (Kakati et al. 2015).
Among infectious diseases, salmonellosis (Rahman et al.
2001, 2003) is more common among captive hogs. An instance
of classical swine fever has also been reported (Barman et al.
2012). Neonatal diarrhoea caused by Escherichia coli is fairly
common in captivity (Narayan et al. 1999b) and the occurrence
of mucormycosis, a fungal infection, has also been recorded
among young captive hogs (Chakraborty et al. 1999). There
was also a report of bacterial infection caused by Actinomycetes
(Macdonald et al. 1990)..02412:46:11