Part II: Species Accounts154
piglets in three different litters in European institutions (see also
Table 14.1 for more details). However, these record litters may
be due to the captive conditions with abundant food resources
and protection from predators. In suitable environmental con-
ditions, females can give birth every 8–12 months (ISIS 2005).
Sexual maturity is reached at an age of two to three years for the
females and at two years for males, although they are still not
fully developed at such a young age. In the wild, Visayan warty
pigs are thought to live up to 15 years (Lastica 2003). The record
lifespan in captivity is 18 years (ISIS 2005).Behaviour
Very little information is available on the behaviour of this
species in the wild and most observations come from captive
animals. Visayan warty pigs have been observed to wallow in
mud, at least in captivity (Lastica 2003; Figure 14.5), but it is
thought that this behaviour is also present in wild individuals.
Observations of grouping behaviour in the wild are also rare,
although it is thought that the species lives in social groups of
up to 12 individuals in remote and undisturbed areas (Oliver
et al. 1993). Observations from captive conditions confirm
the potential social nature of the Visayan warty pig. Similarly
to other Sus species, groups are constituted of one adult male
and several females with their offspring of different age (Rabor
1977; Oliver et al. 1993). There are reports of lone males, but it
seems that these observations are rare. Sows in captivity aggres-
sively defend their nests and offspring from other pigs in enclo-
sures. However, when the piglets leave the nest other boars can
approach them without being attacked by the sows.Parasites and Disease
There are no observations reported of parasites in this species or
of disease transmission to livestock.Status in the Wild
The Visayan warty pig is listed as Critically Endangered by the
IUCN Red List, but is not listed by CITES (2009). It has been
extirpated from about 95 per cent of its former range and
small populations only survive in isolated small forest areas
(Cummings 2003; Oliver 2004).
The main causes that have contributed to the drastic decline
of this species are habitat loss, illegal hunting and hybridiza-
tion with free-ranging domestic pigs (Oliver 2004, 2008, 2009).However, due to the critical conservation status of the last
remaining Visayan warty pig populations, the IUCN/SSC Pigs,
Peccaries and Hippos Specialist Group (now Wild Pig Specialist
Group), the Zoological Society of San Diego and the Rotterdam
Zoo with the collaboration of the Philippine Government’s
Department of Environment & Natural Resources (DENR),
developed a ‘Visayan Warty Pig Conservation Programme’ in
1993 (Oliver 2004, 2008, 2009). These parties have identified the
following main objectives:
(a) increase the surveys in the last remote areas where the
presence of this species is probable and implement
education awareness campaigns, diverse personnel
training, and other local capacity-building initiatives;
(b) improve the conservation status through the development
of new protected areas and establish proper breeding pro-
grammes in Negros and Panay islands;
(c) rescue live animals illegally caught in snares by local hunters
to use them as founders in breeding centres;
(d) validate the genetic purity of any such founder in order to
also ensure the purity of the separate stocks from Negros
and Panay as there are important genetic differences
between these populations; and
(e) export individuals bred in captivity from Negros and Panay
islands to Rotterdam and San Diego zoos and to other
approved breeding centres in the USA and Europe.
A new genetic study by Nuijten et al. (2016) found some evi-
dence for a recent split between the two populations in Panay
and Negros. These pigs were sequenced and showed a similar
demographic history. Proof for both past and recent inbreeding
indicated that the founders were at least to some extent related.
Furthermore, the low level of nucleotide diversity compared to
other Sus species potentially poses a threat to the viability of the
captive populations.Status in Captivity
This highly endangered species is a priority in conservation
terms for the TAG Regional Collection Plan; therefore, both
American and European Associations of Zoos and Aquaria
are focusing efforts to achieve a healthy and viable population
of Visayan warty pig. The member institutions are encour-
aged to join the breeding programme and to contribute finan-
cially to the Visayan Warty Pig Conservation Programme in
the Philippines (source: EAZA 2015). The European captive
population in 2015 has slightly decreased from 147 individu-
als to 144, at the same time the number of holding institutions
has increased to 30, as two new institutions have joined the
European Endangered Species Programmes (EEP). Although
this is a healthy population, the main issue is that it is based on
only five founders. Gene diversity is 82 per cent and to keep it
at 90 per cent in the next 100 years is not possible with the cur-
rent number of founders (EAZA 2015; Liu et al. 2015; Nuijten
et al. 2016).
On the basis of this issue the main targets of EEP are to:
(a) increase the number of holders and continue to breed the
species in the short term until new holders are available; and
(b) find new founders.Table 14.1 Visayan warty pig litter size distribution in European
institutions from 2004 to 2015.Piglets Litters
1 37
2 36
3 45
4 20
5 3
Source: Visayan warty pig EEP SPARKS data set, modified.01612:38:23