Ecology, Conservation and Management of Wild Pigs and Peccaries

Chapter 20: Javan warty pig Sus verrucosus (Boie, 1832) and Bawean warty pig Sus blouchi (Groves and Grubb, 2011)

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study on wild Bawean warty pigs, there have been no immatures
recorded from November 2015 to February 2016, while piglet
numbers were normally distributed in the subsequent months
with a peak in August 2016 (Rode-Margono, unpublished).
As the breeding programme at CCBC has only started to be
successful a few years ago, no data are available about mortality.
The oldest animal recorded at CCBC is estimated to be 7 years,
but longevity is likely to be higher. Nothing is known about mor-
tality or longevity from the wild.

Behaviour

Although historically group sizes of up to 20 animals were
reported, most recent records report a maximum of six individ-
uals for Javan warty pigs during the breeding season and fewer
at other times (Oliver 1993; Meijaard et al. 2011). Adult males
may also be solitary except for the breeding season (Blouch
et al. 1983; own observation). Dominant males of Bawean
warty pigs have been observed and camera-trapped roam-
ing alone as well as joining groups that included piglets and
juveniles (Rademaker and Rode-Margono, unpublished data;
Rode-Margono et al. 2016; Figure 20.7). During the months
November–January, camera trapping on Bawean Island sug-
gested group sizes of 2.2 (locations with wallows: 1–6 animals,
mean 2.6; mean at locations without wallows: 1–9 animals, mean
1.8; n = 92) (Rademaker et al. 2016). Although a suitable video
length was chosen, some group members may have been missed
by camera trapping. Adult male to adult female sex ratio was 1:2
(Rademaker et al. 2016). Directly observed groups from August
to November had on average 4.6 individuals (± 1.8, range 1–7)
and 1–2 adult males and females each as well as several juveniles

and/or piglets (Rode-Margono et al. 2016). This higher number

as compared to the camera-trapping study may stem from an

absence of immature animals in the group as compared to the

direct observations in Rode-Margono et al. (2016).

Behaviour data have been only collected once for Javan

warty pigs in captivity (Rademaker et al. 2015), and once for

Bawean warty pigs in the wild (Rode-Margono et al. 2016). At

CCBC wild adults kept in pairs were very anxious and quickly

disturbed. In comparison to captive-bred juveniles they

showed less feeding and more alert behaviour. They also stayed

very close to each other (e.g. < 5 m) in the majority of observa-

tions. Furthermore, they spent significantly more time at fences

adjacent to and interacting with neighbouring warty pigs, pos-

sibly indicating that animals may prefer larger social groups

than pairs. Rode-Margono et al. (2016) observed wild Bawean

warty pig groups on 12 occasions, always in open forest planta-

tions, between 17:00 and 18:00. Almost two-thirds of the obser-

vations were behaviours related to feeding and foraging. The

group was rather cohesive. Interestingly, in contrast to captive

Javan warty pigs, wild Bawean warty pigs were very bold

and curious as they approached the observers up to about

3 m (Rode-Margono et al. 2016). Warty pigs raise their dorsal

crest and hold the tail erect when they are alarmed. The alarm

call is a shrill whistle. Tusk marks are left on trees and are dis-

tinct from the scratch marks left by the sympatric Bawean deer

(Axis kuhlii). Tusk marking is probably associated with scent

marking by facial glands aiding in olfactory communication,

as common for other Suidae species. The lobe glands present

on the fore-legs are scent glands that aid communication as

has been shown in domestic pigs Sus domesticus (Heise-Pavlov

Figure 20.7 Male Bawean warty

pig (Sus blouchi), Bawean Island

(photo by Dinda Rahayu Istiqomah,

Bawean Endemics Conservation

Programme BEKI).

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