it avoids filling the monkey's stomach with wasteful bulky seeds that cannot be used for energy. It also can help the plants by distributing seeds to new areas: Crab-eating macaques eat durians such as Durio graveolens and D. zibethinus, and are a major seed disperser for the latter species. Although the crab-eating macaque is ecologically well-adapted and poses no threat to population stability of prey species in its native range, in areas where it is not native, it can pose a substantial threat to biodiversity. Some believe the crab-eating macaque is responsible for the extinction of forest birds by threatening critical breeding areas as well as eating the eggs and chicks of endangered forest birds. The crab-eating macaque can become a synanthrope, living off human resources. It feeds in cultivated fields on young dry rice, cassava leaves, rubber fruit, taro plants, coconuts, mangos, and other crops, often causing significant losses to local farmers. In villages, towns, and cities, it frequently takes food from garbage cans and refuse piles. It can become unafraid of humans in these conditions, which can lead to macaques directly taking food from people, both passively and aggressively. Tool use In Thailand and Myanmar, crab-eating macaques use stone tools to open nuts, oysters and other bivalves, and various types of sea snails (nerites, muricids, trochids, etc.) along the Andaman sea coast and offshore islands. Another instance of tool use is washing and rubbing foods such as sweet potatoes, cassava roots, and papaya leaves before consumption. Crab-eating macaques either soak these foods in water or rub them through their hands as if to clean them. They also peel the sweet potatoes, using their incisors and canine teeth. Adolescents appear to acquire these behaviors by observational learning of older individuals. Distribution and habitat The crab-eating macaque lives in a wide variety of habitats, including primary lowland rainforests, disturbed and secondary rainforests, shrubland, and riverine and coastal forests of nipa palm and mangrove. They also easily adjust to human settlements; they are considered sacred at some Hindu temples and on some small islands, but are pests around farms and villages. Typically, they prefer disturbed habitats and forest periphery. The native range of this species includes most of mainland Southeast Asia, from extreme southeastern Bangladesh south through the Malay Peninsula and Singapore, the Maritime Southeast Asia islands of Sumatra, Java, and Borneo, offshore islands, the islands of the Philippines, and the