Chapter 20: Javan warty pig Sus verrucosus (Boie, 1832) and Bawean warty pig Sus blouchi (Groves and Grubb, 2011)195
the assumption that warty pigs are restrictied to altitudes below
800 m a.s.l. (Blouch 1988). Bawean warty pigs occur on Bawean
Island, a 192 km^2 island situated in the Java Sea approximately
120 km north of East Java and 250 km south of Kalimantan,
Indonesia (Hoogerwerf 1967; Nijman 2004; Rademaker et al.
2016). Administratively, the island belongs to the regency of
East Java. Because the two taxa are considered as full species
there are no subspecies (Groves & Grubb 2011).Descriptive Notes
Differentiating the species in the wild is difficult (for comparative
physical characteristics see Table 20.1), except for pure adult male
Javan warty pigs due to the distinct warts on their face. While the
face of warty pigs seems to be elongated, body dimensions and
proportions can be misleading from a distance. In comparison to
European wild pigs, where both sexes have similar body sizes and
weights, there is a pronounced sexual dimorphism in warty pigs,
with males sometimes reaching double the weight of females
(Meijaard et al. 2011). However, measurements in the field have
also shown adult male Bawean warty pigs with warts that are not
much larger than those of females (Rademaker & Rode-Margono
2015). Groves and Grubb (2011) judge from the skull length
that Bawean warty pigs are smaller than Javan warty pigs (408–
429 mm vs. 354 mm in adult males), and this can be confirmed
by field observations (Rode-Margono and Rademaker, personal
observations). Hoogerwerf (1967, p. 318) cited Alting Sieberg
that the pig species on Bawean island (calling it Sus scrofa milleri
JENTINK) differed ‘from those known from Java because of
their small dimensions, aberrant colour and pointed muzzle’.
Male Bawean warty pigs have a very conspicuous white beard,
while the beard of pure Javan warty pigs is black.
Adult male warty pigs have three paired warts that grow with
age: one pair under the eyes (rostral), one pair on the cheeks
(infraoribital, the largest), and one pair on each side of the nose
(gonial, marked with a tuft of long hair in young males) (Groves &
Grubb 2011). Warts start to grow at about 1.5 years age at approxi-
mately 25–35 kg body weight (Meijaard et al. 2011). Compared
to the warts under the eyes and on the nose (2.9 and 3.7 cm long,
respectively, for Javan warty pig), the warts on the cheeks have the
biggest length (12 cm for the Javan warty pig) (Semiadi & Nugraha
2009). Camera trap videos give the impression that adult Bawean
warty pigs have bigger warts (Rode-Margono, unpublished).
Young males have conspicuous sideburns, black in Javan warty
pigs and white in Bawean warty pigs. Some animals of both spe-
cies that have very large warts do not have a beard. Possibly, old
animals with large warts lose their beard, but this has not been
empirically confirmed as the age of most wild animals is unknown
and the majority of registered captive-born males are still young.
Hoof measurements for a single animal are presented
in Semiadi and Nugraha (2009). Warty pigs may have more
pointed toes as compared to S. scrofa, but this needs to be con-
firmed (Meijaard 2006).
Carpal glands are present as four lobes for Javan warty pigs
and three for Bawean warty pigs, located in a row along the pos-
terior of the fore legs and are visible from at least 1.5 months
of age. In contrast, other Suidae species have five to seven lobes
(Farnesi et al. 1999).Figure 20.3 Piglet of Javan warty pig (Sus verrucosus), at CCBC. Warts have
already started to grow (photo by Florian Richter). (A black and white version
of this figure will appear in some formats. For the colour version, please refer to the
plate section.)
pig as separated from Javan warty pigs, based on morphological
measurements from four male skulls and one female skull in the
1980s. Further morphological descriptions, as well as prelimi-
nary genetic analysis (Frantz, personal communication), sup-
port this view and we will treat the Javan and the Bawean warty
pig as distinct species. However, DNA analysis is required to
clarify the exact taxonomic position of the two taxa.
Subspecies and Distribution
Both species are endemic to Indonesia, the Javan warty pig to
the island of Java, and the Bawean warty pig to the island of
Bawean (Figure 20.4 and Figure 20.5). Javan warty pigs on the
island of Madura are believed to be extinct (Semiadi, unpub-
lished data). The exact present distribution of Javan warty pigs
on Java is unknown. Historically it has occurred on the whole
island, and according to local informants is still present in West
Java and the border between Central and East Java, and accord-
ing to local informants and an ongoing camera trap and recce
survey is still present in some areas of West Java and the bor-
der between Central and East Java (Semiadi & Meijaard 2006;
Rademaker 2015; Rode-Margono, unpublished). One record of
Javan warty pigs from 1500 m a.s.l. (Meijaard 2014) challenges
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