Judul: The Sleeping Site Selection of Sulawesi Black- Crested Macaque (Macaca nigra Desmarest 1822) in Tangkoko, North Sulawesi
Abstrak: Monyet jambul hitam Sulawesi (Macaca nigra) merupakan salah satu dari 7 spesies monyet endemik Sulawesi. Populasi M. nigra hanya dapat ditemui di hutan Provinsi Sulawesi Utara dan pulau-pulau kecil di sekitarnya. Persebaran yang sangat terbatas dan tren populasi yang menurun membuat status konservasi M. nigra masuk dalam kategori Kritis (Critically Endangered). Penelitian ini bertujuan untuk menginvestigasi strategi pemilihan lokasi tidur pada Macaca nigra di Kesatuan Pengelolaan Hutan Konservasi (KPHK) Tangkoko, Sulawesi Utara, Indonesia. Penelitian mengenai pemilihan lokasi tidur penting dilakukan untuk memberikan gambaran mengenai proses adaptasi dan strategi bertahan hidup dari suatu spesies. Saat tertidur, kondisi tubuh dalam keadaan tak sadarkan diri dan rentan diserang oleh predator. Lokasi tidur harus dipilih dengan sangat hati-hati untuk memaksimalkan penggunaan energi dan waktu, serta mengurangi resiko ancaman seperti predator. Dua grup monyet jambul hitam Sulawesi (M. nigra) yang telah terhabituasi diamati selama sembilan bulan dimulai dari September 2020 hingga Juni 2021 dengan total waktu pengamatan selama 187 hari atau 2.251 jam. Selama penelitian, M. nigra tercatat menggunakan 20 lokasi tidur yang berbeda dengan lima lokasi di antaranya dipakai oleh kedua grup. Macaca nigra menghindari tidur di lokasi yang sama dengan malam sebelumnya. Dua kali perjumpaan dengan predator (Python reticulatus) terjadi di dekat lokasi tidur tetapi tidak ada monyet yang dimangsa selama penelitian berlangsung. Macaca nigra menggunakan 58 pohon tidur dari 13 spesies tumbuhan. Sebanyak 79% (n=46) dari pohon tidur merupakan jenis pohon yang dikonsumsi oleh M. nigra. Secara umum, spesies ini memilih tidur di pohon dengan ketinggian 30 meter, diameter besar, dan kanopi rimbun agar dapat melindungi diri dari predator, menampung seluruh anggota grup, dan melindungi dari cuaca buruk. Jarak rata-rata antara pohon tidur dan pohon pakan yaitu 203 meter di pagi hari dan 127 meter di sore hari. Macaca nigra mengeluarkan suara loud call secara intens pada jam 05.00 – 07.00 dan jam 16.00 – 18.00 WITA. Loud call berperan sebagai sinyal komunikasi kepada grup monyet lainnya agar bisa menghindar dari kompetisi intergrup. Hasil penelitian ini menunjukkan bahwa M. nigra memilih lokasi tidur sebagai strategi untuk menghindari predator, mendapatkan makanan, dan menghindari kompetisi dengan grup lain. Penelitian bermanfaat untuk memberi gambaran yang lebih luas akan preferensi habitat dan strategi yang dilakukan M. nigra untuk kelangsungan hidupnya. Hasil penelitian ini dapat menjadi rekomendasi untuk menentukan titik lokasi patroli, pemasangan kamera jebak, serta acuan untuk survei kelayakan lokasi pelepasliaran.
Keyword: Macaca nigra, monyet jambul hitam Sulawesi, pemilihan lokasi tidur

Judul: Perilaku Harian Monyet Hitam Sulawesi (Macaca nigra) pada Masa Kebuntingan di Cagar Alam Tangkoko-Batuangus, Sulawesi Utara
Abstrak: Crested macaque (Macaca nigra), one of the seven endemic primates in Sulawesi is the most endangered macaque species that has been categorized as critically endangered by International Union for Conservation of Nature (IUCN). However, almost nothing is known about the reproductive biology in associated with the behavioral during pregnancy. The data is important to support a management and breeding programs such as pregnancy diagnostic and conservation program in this species. The research aimed to study the behavior of the crested macaques during pregnancy. Observations were performed on the 10 adult females of the Rambo 1 group (R1) which has been habituated at Tangkoko-Batuangus Nature Reserve, North Sulawesi. Behavioral data were collected using focal animal sampling and recorded using instantanaeous sampling on females during menstrual cycling, pregnancy, and after parturition (lactation). During five months observations, a total of 393,63 observation hours were recorded. The results showed that daily activities of the M. nigra during menstrual cycling were dominated by feeding (26.60%), foraging (15.95%), and locomotion (16.16%). Daily activities during pregnancy were dominated by feeding (27.03%), foraging (16.37%), and resting (13.45%), whereas after parturition (lactation) period was dominated by resting (26.12%), foraging (19.51%) and feeding (14.98%). The resting was the most activity in the end of pregnancy and few day after parturition. The diets which were collected successfully composed of the fruits (34 species, 20 families), arthropods (3 species, 2 families, 4 orders), fungi (4 genera and division), and plants (5 species and families). Climate influenced on the composition of the diet, especially on fruit and arthropods. In conclusion, the activity budgets were different during menstrual cycling, pregnancy, and lactation, especially feeding, foraging, locomotion, and resting.
Keyword: Bogor Agricultural University (IPB), diet, lactation, pregnancy, menstrual cycling, M. nigra

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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