Judul: Foraging skill learning of immature Tapanuli orangutans at Camp Mayang Research Station, North Sumatra.
Abstrak: One of the most important skills to learn during postnatal development period is foraging skill. It is apply to orangutans’ need in their complex foraging niche, broad diets, and highly fluctuating food availability in the natural habitat. Study about this behavior in Tapanuli orangutans (Pongo tapanuliensis) has never been described yet. Therefore, the aim of this study was to observe the foraging skill learning of immature Tapanuli orangutans at Camp Mayang Research Station, North Sumatera. I did the observation with focal animal sampling of immature individual and its mother as references. Data analysis was performed using Kruskal Wallis test and corrected with False Discover Rate. I found that the infant had high independency on social feeding behavior toward its mother, high similarity of diet repertoires and food processing steps with the mother. Moreover, the infant still depended on the mother to find feeding patches and travelling through the forest. The results indicated that foraging skill learning of infant Tapanuli orangutan happened vertically, from the mother to the infant.
Keyword: diet repertoires, food processing steps, Pongo tapanuliensis, postnatal development, social feeding behavior

Judul: Manajemen Pakan Orangutan Sumatera (Pongo abelii Lesson, 1827) di Pusat Reintroduksi Orangutan Sumatera (PROS) Provinsi Jambi
Abstrak: One effort to conserve orangutans population in their natural habitat was by reintroduction. In reintroduction stage, orangutans temporarily live in socialization cage and feed as necessary for introduction to ensure their survival in the wild. Success of orangutan survival in nature could be reached through good management, including orangutan’s food management. Research is needed to identify food and feeding management in a reintroduction activity, to study the feeding duration of orangutan based on feeding frequency, and to study feeding habit of orangutan in socialization cage. Data was collected in June to September 2011 in Sumatran Orangutan Reintroduction Center (SORC) located in two stations: SORC Sungai Pengian Station (Tebo District, Jambi Province) and Open Orangutan Sanctuary (OOS) Danau Alo Station (West Tanjung Jabung District, Jambi Province). Data collection was including primary and secondary data that consist of feeding management, feeding duration, orangutan’s feeding habit, cage management and orangutan’s health management. Focal Animal Sampling methods was used to know orangutan’s feeding habit. Data was analyzed descriptively and qualitative. There were 6 orangutans used as samples, representing different sexes and age structures. Orangutan’s food management in socialization cage was categorized based on food type, feeding time, food preparation, and feed presentation. There were 4 types of food: main food, enrichment food, natural food, and additional food. The main food was given 5 times a day. Food type and main feeding time was arranged based on food management by considering diet of orangutan’s food. The fastest average feeding time was by orangutan named Frangkie (sub adult, female; averaging 3 minutes 52 seconds), while the longest was in orangutan named Mirriam (juvenile, female; 20 minutes 12 seconds). Management implementation was supported by reintroduction to natural habitat, Mobile Educational Unit, Wildlife Protection Unit and Community Development. Feeding duration of orangutan was affected by food type, method of food provision, method of feed preparation and feeding habit of orangutan. Feeding management in reintroduction centre was needed to increase enrichment food and natural food. In addition, further research about proximate analysis is needed, as well as changing food container
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Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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