Activity Budgets and Habitat Use of Wild Southern Pig-Tailed Macaques (Macaca nemestrina) in Oil Palm Plantation and Forest

Abstract

Conversion of primary rainforest to agricultural land causes habitat loss and fragmentation and is a major threat to wild primates worldwide. Conversion of forest to oil palm plantations (Elaeis guineensis) is a particular problem, so it is important to understand whether and how primates use such plantations. Populations of southern pig-tailed macaques (Macaca nemestrina) are declining in Peninsular Malaysia due, in large part, to conversion of primary forests to oil palm plantations. Researchers have observed macaques foraging in plantations but little information is available about how macaques cope with the expansion of plantations into their habitat. We collected GPS data on the home range of a group of wild pig-tailed macaques that foraged in both habitat types in May 2013–May 2015, and compared their use of oil palm plantation and primary rainforest by recording their activity budgets and analyzing their habitat use and diet in both habitat types 4–6 days per week in October 2014–December 2015. The group visited the plantations daily. In 2013–2014, 17% of the group’s overall home range core area (0.6 km2) was in oil palm plantations and in 2014–2015, this increased to 28%. However, the macaques spent most of the day time in the forest and always used a sleeping tree in the forest. Macaque activity budgets in the plantation were significantly different from those in the forest. Feeding and foraging comprised a significantly larger proportion of their activity budget in the plantation, while locomotion, resting, and social behaviors occurred significantly more often in the forest. In both habitats, macaques spent most of their time on the ground and foraged primarily on the ground in the plantation. Of food items eaten in the plantation 85% were oil palm parts, including attached and fallen oil palm fruits and seeds, and flowers. Oil palm plantations serve as additional foraging ground for these macaques, but our results also show that the forest is essential, providing a greater dietary diversity and sleeping sites and allowing resting and social activities. It is not clear to what degree pig-tailed macaque populations can adapt to human-altered environments in the long term. Although our study group used oil palm plantations as regular foraging and feeding ground, pig-tailed macaques are also closely associated with the rainforest habitat, and the protection of natural forest is essential for their conservation.