Dark-Sky Habitat Assessment: Dreketi River Region, Vanua Levu, Fiji

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eCoast's latest project for the International Dark-Sky Association evaluated Fiji’s Dreketi River region for dark-sky habitat potential, highlighting threats from artificial light to endangered nocturnal species. The project offers critical conservation insights and lighting recommendations to protect key wildlife such as the Fijian free-tailed bat and juvenile sharks.

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Information:

• Location: Dreketi River Region, Vanua Levu, Fiji
• Client: International Dark‑Sky Association (IDA), NZ Chapter
• Project Date: 2025

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Scope of Work:

• Identification and evaluation of dark-sky candidate habitat
• Survey of threatened terrestrial and freshwater species
• Assessment of light pollution impacts on nocturnal fauna
• Recommendations for ecological light management and IDA certification

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                                                        ^{Source: National Trust of Fiji, 2018}

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Project Description:

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This study assessed the dark-sky potential of Fiji’s Dreketi River region and the impacts of night lighting on local wildlife. Field surveys found that this tropical island ecosystem hosts critical habitats: for example, the Nakanacagi Cave (near the site) contains the only known maternity roost of the endangered Fijian free-tailed bat (over 95% of its global population). The adjoining Dreketi River estuary is a rich elasmobranch nursery – juvenile bull sharks (vulnerable) and endangered hammerhead sharks were documented in substantial numbers. Overall, five nocturnal species of conservation concern were identified near the project (two bat species, two frog species, and bull sharks). The report highlights that artificial light at night (ALAN) can disrupt these sensitive tropical fauna–altering frog and bat behaviour and shark physiology–with serious conservation implications.

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Key Recommendations:

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Mitigation focuses on avoidance and light control. Dark corridors around the bat cave and river should be maintained with buffer zones of low illumination. Lighting must be shielded, downward-directed, and warm-white (≤2700 K) to reduce skyglow and disturbance. Timers, dimmers, and removal of unnecessary fixtures will further limit impacts. Ecological surveys (bats, frogs, insects) are needed to map key habitats and inform design. Early planning should prioritise avoidance, keeping vegetation corridors and dark refuges intact. Community engagement with indigenous leaders and integration of mātauranga Māori will ensure cultural alignment. Linking dark-sky certification with biodiversity protection, education, and eco-tourism will deliver both conservation and community benefits.

                                                 ^{Source: Bat Conservation Trust, 2023}

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