The presence and distribution of small carnivores in oil palm plantation and their role in controlling rat damage: preliminary results from a camera trapping study

The presence and distribution of small carnivores were investigated in two oil palm plantations using camera-traps. Eight camera-traps - four in Rama-Rama estate and four in Libo estate (Riau Province, Indonesia) - were set up in March 2012. Two cameras were located near a protected forest, three near a conservation area two in the centre of the oil palm plantation, and one near a settlement. The camera-traps were successful in photographing three small carnivore species (leopard cat, Prionailurus bengalensis; common palm civet, Paradoxurus hermaphroditus; Malay civet, Viverra tangalunga) and one reptile (monitor lizard, Varanus salvator), which are all predator of rats. Preliminary analyses suggest that the distribution of small carnivores and reptiles were affected by habitat features in the oil palm plantation, such as settlement and conservation areas. The camera traps set near the protected forest and conservation area photographed more frequently predators of rodents, suggesting that these areas may play an important role for small carnivores (such as providing daytime resting sites). In general, small carnivores were photographed as early as 18:00 - 19:00h (when they start to hunt and search for food) until 06:00 - 07:00h (when they return to their daytime rest site). Over the past 15 years, the barn owl (Tyto alba javanica) has been propagated in oil palm plantations in Riau Province in order to control rat populations. The presence of small carnivores and the monitor lizard is complementary to the barn owl for maintaining rat damage below economic threshold, as indicated by a rat damage census for the last five years in Libo and Rama-Rama estates. A preliminary finding of our study suggests that conservation areas in oil palm plantations may help promote the diversity of small carnivores and reptiles, which in turn will keep rat damage stable at a low level. This study has now been enlarged with 10 additional camera-traps, and a later full analysis of all the data may confirm the preliminary results presented here. (Résumé d'auteur