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Chapter 22: Pygmy hog Porcula salvania (Hodgson, 1847)such drives were conducted in an area of about 10–12 km^2 under
Bansbari Range of Manas National Park over a period of six days
in mid March 1996, using 9–13 elephants and about 25 beaters
on foot. Altogether, 42 individual pygmy hogs were flushed, of
which 11 were captured in the process. Six of these hogs (three
adult females, one adult male, one subadult male, and one sub-
adult female) from five different locations were transferred to
the breeding facility in Basistha. The other five (four male and
one female) were released promptly at the capture site after fit-
ting three of the males and the female with radio harness for
radio-telemetry studies.
Conservation Breeding
Fortunately, all three adult sows captured in Manas were preg-
nant from the wild and produced three healthy litters, compris-
ing a total of 13 (seven male and six female) young, all but one
of which were successfully reared. The captive breeding strat-
egy included mating the same pair of hogs year after year and
producing unrelated family lines within which no mating was
allowed. Another seven litters were born in 1997, of which 24
(15 male and nine female) young were reared. With similar suc-
cess in the first 5-year period, this population increased by about
13 times to 77 (40 males and 37 females), which included four of
the original founders.
While these results greatly exceeded expectations, contin-
ued breeding at the same rate could have caused overcrowding
in captivity. Unfortunately, the animals could not be released
into the wild due to the prevailing security situation in and
around the potential release sites, and the scarcity of funds to
establish a ‘pre-release’ facility. The reintroduction process was
started after the conditions improved almost five years after the
programme was ready to release animals. Meanwhile, a captive
population of about 70 hogs was maintained between 2002 and
2006 by breeding only a limited number of animals at Basistha
centre (Figure 22.5).
Preparation for release into the wild began in 2007 and accord-
ingly the number of breeding pairs was increased to produce hogs
for reintroduction. A second breeding centre was developed at
Potasali adjoining the ‘pre-release’ facility (Figure 22.3). This
was also necessary to reduce the risk of any catastrophic event
because the entire global population of captive pygmy hogs were
at one site. Since 2007, about 11–12 captive-bred hogs have been
removed from the breeding population each year for release,
while maintaining a captive population of around 60–65 animals
at the two centres.
In the 20-year period between 1996 and 2015, altogether
132 litters consisting of 530 (260 male, 261 female and nine
unsexed) hogs were delivered in captivity and 323 (165 male
158 female) hogs, or 61 per cent of the young, were reared beyond
three months. This was in sharp contrast to the rearing rate of
just 28 per cent in 14 litters (considering only reliable records)
born in captivity between 1883 and 1979 at the tea estates in
Assam, and in London, Zurich and Assam State Zoos (Oliver
1980). The average litter size in the above 132 litters at Basistha
and Potasali was 4.02 compared to 3.57 in the 14 records to 1979
(Oliver 1980).
Selection of Potential Reintroduction Sites
One of the objectives of the extensive surveys between 1995
and 2005 was to identify future reintroduction sites, and three
potentially suitable sites in north-western Assam – Sonai Rupai
Wildlife Sanctuary, Nameri National Park and Orang National
Park were shortlisted in consultation with local stakeholders.
After 2010, a fourth site – Barnadi Wildlife Sanctuary –was also
added to this list as the protection improved in the PA. These four
sites fall within the known range of the species, although no evi-
dence could be found of its continued occurrence at these sites.
Eventually, Sonai Rupai, located about 150 km east of Manas,
was selected for the first releases in 2008 as it was possible to
quickly restore the relatively small and secure grasslands in the
Gelgeli area of the sanctuary. On the other hand, the Dekorai
grasslands in southern part of Nameri continued to suffer from
livestock grazing and were difficult to protect. The grasslands
in Orang were also suitable, but some areas of the Park experi-
enced extensive flooding during monsoon, so the Park was kept
under observation for a few years to assess floodwater levels in
the grasslands. Later it was found that many grassland areas inFigure 22.5 Adult individual at Basistha breeding centre with his keeper
(photo by R. Wirth). (A black and white version of this figure will appear in some
formats. For the colour version, please refer to the plate section.).02412:46:11