Taiwan Rhesus Monkey is a gregarious animal, found to be inhabited only Taiwan. Many Taiwan Rhesus Monkeys are kept in the center, either because they were confiscated by the government or abandoned by their owner. Most of the monkeys lack gregarious experience to live in the wild. Thus, these monkeys will be formed into a proper-sized group to regain their survival ability in the wild. Eventually, they will be sent to a more natural environment. These hand-reared monkeys, however, once released in the wild, may bring negative effects toward the present wild species, such as competition for living space, importing diseases, and so on.

To avoid these problems, in 1995 we started to observe several Penghus islands. The first release point chosen was located at Sijiaoyu Island, covering an area of 13 ha, some 780 m from Feng Guiwei, Magong. There are no particular wild species on the island and plant species are rather simple. A variety of invertebrates an ideal food for monkeys and fresh water was also available on the island. In 1998 and 1999 20 monkeys were released on Sijiaoyu Island. Each released individual not only adapted easily to the new environment and the climate, but also learned to take advantage of the available resources on the island in a short-term. The appearance, physical strength and actions of each individual in the new environment are obviously superior to those of hand-reared monkeys. More monkeys, therefore, will be released later.