Susan Island Nature Reserve: An Ecologically Significant Protected River Island Landscape

Susan Island has a long history of human use that long predates its formal protection. The Gumbayngirr people regularly visited the island for fishing, hunting, and gathering rainforest foods, medicines, and plant fibres used in making bags and nets. The island carries enduring spiritual significance for the Gumbayngirr community and is recognised as a Women's Site, a reflection of gendered cultural responsibilities connected to the land and the river.

European arrival brought dramatic change. Most of the rainforest on the island was cleared, first through timber harvesting; red cedar in particular was logged from the island until the 1920s, when the accessible supply was exhausted and natural regeneration had effectively ceased. Open land was also used for cattle grazing and for the establishment of Grafton's first rifle range. These activities reduced the original forest to a small remnant concentrated on the upstream third of the island.

Recognition of the surviving rainforest's rarity eventually led to formal protection. In May 1982, the western upstream portion of Susan Island was gazetted as the Susan Island Nature Reserve, placing it under the management of the NSW National Parks and Wildlife Service. From the late 1980s onward, ongoing restoration programs began confronting invasive weeds, beginning with dense prickly pear infestations before expanding to deal with the more aggressive exotic vines that characterise modern riparian weed problems in northern NSW. Red cedar was reintroduced to the island in 2001, marking a symbolic and practical reversal of the early logging era. The site was also formally acknowledged as an Aboriginal Place, embedding its Indigenous cultural significance into its contemporary protected-area identity.

Susan Island is a long, narrow river island in the Clarence River, roughly three kilometres long and about 420 metres wide, oriented along the natural course of one of eastern Australia's larger coastal river systems. The reserve occupies the upstream third of the island, meaning that most of its edges are shaped by the river itself and by the dynamics of Clarence River flooding.

The surface of the island is built from alluvium laid down by the Clarence River. Soils are deep, river-deposited materials that drain freely but remain sufficiently moist to support closed-canopy forest. Rainfall in the area is moderate rather than high, averaging around 1,080 millimetres per year, which is just enough to sustain subtropical rainforest on the margins of its climatic range. This combination of river-built soils and moderate rainfall produces what ecologist A.G. Floyd described as a dry form of subtropical rainforest, floristically rich but sensitive to disturbance.

The visible landscape is a layered canopy of tall trees, including large Moreton Bay figs, forest red gums, tulipwood, lacebark, pepperberry, red bean, black bean, and prominent specimens of yellow kamala and white bean, the latter reaching the southernmost limit of its natural distribution on the island. Beneath the canopy, ferns, palms, vines, and a thick litter layer characteristic of subtropical rainforest create a sheltered, humid microclimate that contrasts strongly with the exposed riverbanks that surround it.

The reserve's most important ecological value is its remnant of subtropical lowland floodplain rainforest, a vegetation community that is now listed as Endangered under New South Wales biodiversity legislation. This forest is structurally complex, with a tall upper canopy of emergent figs and eucalypts, a mid-storey of smaller rainforest trees and shrubs, and a ground layer of ferns and seedlings, supported by alluvial soils and a closed microclimate generated by the canopy itself.

More than 100 native plant species are recorded on the island, of which 94 are rainforest trees and shrubs. The community is significant because floodplain subtropical rainforest of this kind has been extensively cleared across the New South Wales coast for agriculture and timber, leaving the river islands of the Clarence among the few places where intact examples still exist. Susan Island holds the largest such remnant in the Clarence Valley, making it a reference site for the conservation of the broader ecological community.

A defining ecological challenge on the island is invasive vegetation. Exotic vines such as cat's claw creeper, Dutchman's pipe, moonflower, and balloon vine have been particularly destructive in northern NSW riparian zones, forming dense curtains that smother and kill native trees and collapse into the understorey once the canopy fails. Camphor laurel and broad-leaved privet add to the pressure. Active management of these weeds and ongoing replanting have been central to keeping the rainforest from collapsing into a degraded vine thicket.

Susan Island's wildlife profile is shaped by the overlap of rainforest, river, and open floodplain habitats. Fauna surveys in the late 1990s and 2000s recorded more than 160 bird species, 12 reptile species, and 15 mammal species on the island, indicating a notably high diversity for such a small reserve.

The single most significant animal feature is the grey-headed flying fox colony. The island has been used as a year-round roost and maternity camp for this threatened species since at least the time of European settlement, and in summer the population grows dramatically as other flying fox species arrive to feed on flowering eucalypt forests nearby. Counts at peak times can exceed 100,000 and sometimes surpass 300,000, often swelled by large numbers of little red flying foxes responding to hardwood blossom events. The noise, movement, and ecological impact of these aggregations make Susan Island one of the more prominent flying fox sites along the New South Wales coast.

Birds are a major draw for visitors and researchers. Threatened and notable species recorded on the island include the white-bellied sea eagle and osprey hunting along the river, the wompoo fruit-dove deep in the forest, the notoriously shy and cryptic noisy pitta, and more common residents such as eastern yellow robins, grey fantails, and Lewin's honeyeaters. Reptiles surveyed include several species typical of east coast riverine environments. Among smaller fauna, Susan Island supports the southernmost known population of Fraser's banded rainforest snail, a striking native mollusc whose range terminates here on the Clarence.

Historical accounts of the island at European settlement suggest a richer mammal fauna than the present, with koalas, gliders, and quolls once recorded. Their decline across the broader landscape is consistent with regional patterns, but their absence on the island today helps frame how much the local mammal community has changed over time.

Susan Island Nature Reserve matters from a conservation perspective because it protects what is now the largest known example of an Endangered Ecological Community in the Clarence Valley: subtropical lowland rainforest on floodplain alluvial soils. Outside this reserve and a small number of related remnants such as Coramba Nature Reserve and Maclean Rainforest Reserve, this vegetation type has been reduced to fragments too small or too disturbed to fully function as rainforest.

Formal protection in 1982 was the foundation, but the reserve's conservation role depends on active management. Since the late 1980s, the NSW National Parks and Wildlife Service has run a long-term rainforest regeneration program targeting invasive weeds, with particular emphasis on fast-growing exotic vines that have devastated riparian rainforest across northern NSW. Initial work focused on dense stands of prickly pear, but the program has expanded to include cat's claw creeper, Dutchman's pipe, moonflower, balloon vine, camphor laurel, and broad-leaved privet. Parallel restoration efforts have reintroduced red cedar, lost through early logging, and continue to expand the rainforest footprint on the island.

The reserve also has recognised value for threatened fauna. Its grey-headed flying fox population gives it national significance as a maternity and roosting site for a vulnerable species, and its bird and reptile listings include several species of conservation concern. Designation as an Aboriginal Place adds a further dimension, recognising the island's cultural and spiritual values alongside its ecological ones and embedding Indigenous heritage into its management framework.

Susan Island holds sustained cultural significance for the Gumbayngirr people of the Clarence Valley. The island has been used over many generations for fishing, hunting, and the gathering of rainforest food, medicine, and plant fibres that were woven into bags and nets. Beyond practical use, the island is a place of spiritual meaning, recognised specifically as a Women's Site, reflecting the gendered structure of Gumbayngirr cultural responsibilities toward land, water, and ceremony.

This cultural importance has been formally recognised in contemporary protected-area governance. Susan Island has been declared an Aboriginal Place under the New South Wales National Parks and Wildlife Act, an acknowledgement that integrates Indigenous heritage into the management of the reserve. Together with the rainforest restoration work and the wildlife protection efforts, this designation ensures that the island's meaning to the Gumbayngirr community remains an active part of how the reserve is understood and cared for.

The reserve's standout features include the largest remaining subtropical lowland floodplain rainforest remnant in the Clarence Valley, the presence of more than 90 species of native rainforest trees and shrubs, and the successful long-term regeneration program that has brought red cedar back to the island after decades of absence.

Equally distinctive is the massive seasonal grey-headed flying fox colony, which can swell from a permanent resident population to gathering of well over 100,000 animals, sometimes reaching several hundred thousand when little red flying foxes join the camp during eucalyptus blossom events. The cultural status of the island as a recognised Aboriginal Place and Women's Site for the Gumbayngirr community adds a final, distinctive layer to a reserve whose value far exceeds its modest area.

The character of Susan Island changes most visibly through the warmer months, when the flowering of surrounding eucalypt forests triggers the dramatic seasonal influx of flying foxes. Late spring and summer are the period when the island's mammal life is at its most intense, with the canopy alive with movement and the air often carrying the noise of a major camp in full activity. Bird activity remains strong year-round, with resident rainforest species such as the noisy pitta, wompoo fruit-dove, eastern yellow robin, and Lewin's honeyeater offering reliable encounters.

Cooler months tend to bring a quieter atmosphere, with smaller numbers of flying foxes and a calmer feel to both the river and the forest. Rainfall in the Clarence Valley is moderate, but the rainforest interior is sheltered and noticeably more humid under the canopy at any time of year, while the riverbanks remain an accessible vantage point in most seasons.