Nantu

Nantu is a Wildlife Sanctuary (Suaka Margasatwa) in Gorontalo province on the northern arm of Sulawesi, Indonesia, lying in the forested interior roughly 28 kilometres from the town of Paguyaman. Covering around 51,500 hectares (515 km²), it was formally gazetted as a sanctuary in 1999 with an initial area of 312 km² and expanded in 2010 to its current extent by incorporation of the Boliyohuto Protection Forest. ^[1] Nantu is regarded as one of the most important lowland rainforest reserves in Sulawesi and is renowned as a stronghold for some of the island's rarest endemic mammals, including the Vulnerable babirusa and the Endangered lowland anoa, which congregate at a famous mineral salt-lick. ^[2] As a suaka margasatwa, it is dedicated to the strict protection of wildlife and habitat, supported by long-running scientific research and community-based conservation.

Nantu is one of the premier wildlife sanctuaries in Sulawesi, protecting a remarkable assemblage of endemic mammals. It is especially celebrated for the Vulnerable babirusa (Babyrousa celebensis), the unique pig whose upper canines curve back over the snout, and for the Endangered lowland anoa (Bubalus depressicornis), a small forest buffalo — both of which gather at the Adudu mineral salt-lick. ^[1] Other endemic mammals include Heck's macaque (Macaca hecki), endemic to the Gorontalo region, Sulawesi cuscus and the spectral tarsier, while birdlife features the maleo, knobbed hornbill and many endemic forest species. ^[2] This concentration of rare and threatened Sulawesi wildlife, much of it found nowhere else on Earth, makes Nantu a globally significant conservation priority.

Nantu protects extensive intact lowland and hill tropical rainforest, among the best-preserved in northern Sulawesi, with over 300 documented tree and plant species. ^[1] The forest is dominated by tall dipterocarps and large fig trees, with a multi-layered canopy and an understorey of rattans, palms, ferns and shrubs, and abundant epiphytic orchids and lianas on the larger trees. Fruiting figs are particularly important in sustaining the reserve's primates, hornbills and other frugivores. The relatively undisturbed and continuous nature of this forest is crucial for the wide-ranging endemic mammals it supports, and it preserves a rich diversity of plant species typical of Sulawesi's threatened lowland forests.

Nantu occupies the forested interior hills of Gorontalo's northern peninsula, within the volcanically and tectonically complex landscape of northern Sulawesi. Its terrain ranges from lowland river valleys to rising forested hills built from volcanic and sedimentary rocks. The reserve is drained by the Paguyaman River and its tributaries, which shape its valleys and support its forest. A key geological feature is the natural mineral salt-lick known as Adudu, where mineral-rich ground and water attract babirusa, anoa and other wildlife, an asset directly tied to the local geology that makes Nantu so valuable for observing these rare animals. ^[1]

Nantu has a hot, humid equatorial climate with temperatures typically in the mid-20s to low-30s Celsius and little seasonal temperature variation, somewhat cooler on the higher hill slopes. Rainfall follows the monsoon patterns of the Tomini Bay region, with wetter and comparatively drier periods through the year, though the lowland rainforest remains moist in all seasons. High humidity and frequent rain sustain the dense forest and the rivers that flow through it. The relatively drier months provide more favourable conditions for fieldwork, patrols and wildlife observation at the salt-lick.

The forests of the Paguyaman region have long been known to local Gorontalo communities, who used the woodland for hunting and forest products and held traditional knowledge of its wildlife, including the babirusa and anoa. The area gained scientific prominence in the late twentieth century through research that highlighted its exceptional endemic fauna and helped drive its formal protection in 1999. Communities living around Nantu remain important partners in its conservation, and efforts have sought to involve them in guarding the forest and benefiting from research and conservation activities rather than relying on hunting or forest clearance.

Nantu was formally designated a wildlife sanctuary in 1999 with an area of 312 km², following research and advocacy that revealed its outstanding importance for endemic Sulawesi mammals, particularly babirusa and anoa. ^[1] The sanctuary was expanded in 2010 to 515 km² by incorporating the adjacent Boliyohuto Protection Forest. The suaka margasatwa status places a primary emphasis on protecting wildlife and habitat, and the reserve has since been a focus of long-term scientific study and community-based conservation, often supported by international partners. It is managed by BKSDA Gorontalo under Indonesia's Ministry of Environment and Forestry, working alongside conservation organisations to protect the forest, guard the salt-lick and combat poaching of its rare fauna.

Nantu's outstanding attraction is its natural mineral salt-lick (Adudu), where babirusa, anoa and other wildlife congregate, offering rare opportunities to observe these elusive endemic mammals in the wild — up to forty babirusa have been recorded at the lick at one time. ^[1] Access is geared toward research and carefully managed conservation visits rather than mass tourism, and reaching the reserve typically involves travel along the Paguyaman River and through the forest with guides and official permission. The pristine lowland rainforest, with its rich birdlife and primates, is itself a major draw for naturalists. Any visit centres on quiet wildlife observation and supporting conservation rather than developed recreational facilities.

Nantu lies deep in the forested interior near Paguyaman, around 28 kilometres from the town and reached from Gorontalo city via road and then river or forest travel. As a wildlife sanctuary, it has minimal visitor infrastructure, and access generally requires authorisation from BKSDA Gorontalo and coordination with the conservation organisations active in the reserve. There are no developed accommodations within the sanctuary; researchers and visitors rely on field camps, ranger posts and local guides. Anyone permitted to enter should be prepared for remote, basic conditions, river travel and the logistical challenges of reaching a largely undisturbed rainforest.

Conservation at Nantu is dedicated to protecting its rare endemic mammals, especially the Vulnerable babirusa and Endangered anoa, from poaching and habitat loss, with the Adudu salt-lick a particular focus for patrols and monitoring. ^[1] BKSDA Gorontalo, together with long-standing conservation programmes and research partners including YANI, conducts anti-poaching patrols, scientific study and community engagement to maintain the integrity of the forest. Involving local communities through education, employment as rangers and guides, and shared benefits is central to reducing hunting and encroachment. Sustaining Nantu's exceptional biodiversity depends on keeping its lowland rainforest intact and its endemic wildlife safe in one of Sulawesi's most important conservation strongholds.