A Supplemental HCVF Assessment on the Sumatran Tiger ...

FINAL REPORT Tiger <strong>HCVF</strong> <strong>Supplemental</strong> <strong>Assessment</strong> – Serapung FMU
5 Discussion
5.1 Tiger Habitat and Prey
The forest remaining within the indicative <strong>HCVF</strong> moratorium area is structurally
degraded; many of the larger “commercial” trees have already been removed and the
water table has been lowered through an intensive system of primary and secondary
canals leading to the FMU’s central log-collection point. However the moratorium area
remains contiguous with the wider Siak-Pelalawan forest landscape. Despite this
degradation and the effects of ongoing illegal logging it was found, through
photographs, secondary signs, tiger faeces and direct sightings, to contain all of the
common prey species of tigers (i.e. sambar deer, muntjak deer, wild boar, and
macaque). The number of secondary signs and frequency of photographs obtained by
camera traps, for prey species both inside and outside the FMU, approximates to that
which is observed in other Sumatran lowland forests where tigers are known to exist. In
some areas of the FMU (e.g. in the Tandjung Datuk peninsular) there was evidence for
prey species’ abundance being markedly higher than that found in many other
comparable lowland forests. This widespread, high abundance of prey and non-prey
species is contrary to expectations based on previous studies in PSF (see: MacKinnon
et al. 1996, Whitten et al. 2000). However, the PSF habitat within the FMU is highly
modified and possibly temporarily “improved” with respect to herbivores, due to
increased secondary growth as a result of logging and forest clearance (see Section
2.3.1: Habitat Modification of PSF by Logging).
Three of the 11 samples of tiger faeces examined were found to contain sun bear
(Helarctos malayanus). Sun bear is not considered a preferred prey species although
predation on sun bears has been occasionally observed in Way Kambas (Franklin
pers. obs.) and in Malaysia (Kawanishi 2002). While it might be hypothesised that preyselection
on sun bear is a response to paucity of the other preferred prey species, it
may also be a reflection of the high density of sun bear in these forests as confirmed by
local people.
Prey abundance was found to be much reduced, or prey species were entirely absent,
in areas of the FMU that had already been cleared and planted with Acacia.
Considering that industrial timber plantations are likely to be a longer term feature of
the landscape, further study should be conducted on this point, examining prey species
abundance (as a measure of suitability as tiger habitat) in relation to age of stands,
density of planted trees and spatial position relative to remaining natural forest areas.
5.2 Tiger Population in and around the FMU
Two adult male tigers were identified from remote camera photographs and the
presence of an adult female was detected from secondary signs. A female tiger with 2
juveniles was reliably sighted in late 2004, confirming that a breeding population of
tigers is present in and around the FMU.
The wide distribution of tiger sign suggests that tigers utilise the majority of the
moratorium area in the FMU, although activity was more concentrated in areas further
from the coast. Although the density of tiger sign within the FMU was found to be
equivalent to that expected in other lowland forest habitats, it was considerably less
than that found along the Yos Trail to the north-west of the FMU. The habitat around
the Yos Trail, despite its association with human settlement, is likely to have an
increased importance for tigers, representing a favoured micro-habitat. Tigers make
use of trails to facilitate efficient coverage of their home range (Franklin 2002), while
“scent-marking” with particular intensity at territorial boundaries between individuals
Sumatran Tiger Conservation Program Pg 45/68