Ranging patterns in Sumatran tigers 2003 – 04

A key strategy for ensuring the survival of the Sumatran tiger is to work on their survival outside the protected area system. Non-protected areas represent a far larger area of land, do not exclude people and therefore reduce the potential for land use conflict, and can provide connectivity between the core protected areas. 

This ZSL project began researching how tigers can survive outside protected areas. Potential for coexistence between tigers and commercial land use had already been shown in an oil palm plantation, PT Asiatic Persada (AP), in Sumatra. A combination of the plantation’s readiness to adopt a management system sympathetic to tiger conservation and the  ZSL’s belief in the importance of engagement with industry for conservation has resulted in the formation of the Jambi Tiger Project, a unique partnership between a conservation NGO, LIPI, and a commercial agricultural company that aims to establish how tigers survive with oil palm and what can be done to ensure the situation persists in a sustainable manner.  

The project combines a core monitoring / protection team run jointly by the plantation and ZSL with a research team that now employs three Indonesian scientists, one British researcher and one Indonesian mechanic. Research objectives for 2003-4 targeted understanding the relationship between tigers, their probable main prey (wild pigs, Sus scrofa) and their role of prey species as pests on the plantation. 

The results show more than 40 medium and large sized mammals using the oil palm concession and borders, with other mammals of conservation interest including tiger(Panthera tigris) dhole (Cuon alpinus), sun bear (Helarctos malayanus), Malayan tapir(Tapirus indicus), clouded leopard (Neofelis nebulosa) and fishing cat (Prionailurus viverrinus) with little difference between the plantation concession and the more intact forest concession. However, use of the oil palm crop itself is limited and almost all species are restricted to the unplanted habitats bordering the oil palm or the Asialog forest concession. However, the degraded scrub habitats showed higher presence of many species than the apparently less degraded forest concession, including the Sumatran tiger.  

Preliminary results from prey studies were based on night transects and randomly placed camera trap surveys. These confirmed wild pigs (Sus scrofa) to be the dominant ungulate and likely tiger prey present, with abundance far outweighing any other species, although at least 19 potential tiger prey species exist on site.

 Research on the tigers based on density calculations from camera trapping rates and individual recognition of camera trap photos show that a minimum of nine and possibly even sixteen tigers have used the plantation concession and bordering areas within the last three years, suggesting densities comparable to many protected areas. At least four of the tigers were breeding residents living within the plantation concession. However, camera trap rates fell sharply in 2003-4 despite prey species and other large mammals apparently remaining stable and based on recent data the tiger population looks to be in severe trouble.

Various avenues still need to be explored before conclusions drawn (for example an expanded survey is needed into the forest concession) but it appears likely that illegal land clearance is looking the most likely cause. 

Tiger movements were also assessed by camera traps and all appeared to use both the plantation and forest concessions. One tiger was also successfully captured and radio collared, the first ever in Sumatra. Despite some complications receiving the signal in certain habitats, data were collected for 7 months before the tiger slipped out of the collar. During this time the tiger spent most of its time in plantation scrub, apparently never venturing into the oil palm. However, estimates of tiger ranges were not particularly improved by the radio tracking data.