The Quokka

Quokkas (Setonix brachyurus) are small macropod marsupials found naturally only in the south-west of Western Australia. They belong to the family Macropodidae, the same family as kangaroos and wallabies, but they are not simply “wallabies”; they are the only living species in the genus Setonix (Australian Museum, n.d.; Gibson et al., 2010).

Although quokkas are now most famous for their population on Wadjemup / Rottnest Island, they also occur on Bald Island and in scattered mainland populations across south-western Western Australia (Gibson et al., 2010; Department of Environment and Conservation, 2013). Historically, quokkas were far more widespread, occupying an estimated 41,200 km² across the region. By 1992, however, their mainland distribution had declined by more than 50%, leaving many populations small, fragmented, and vulnerable to local extinction (Department of Environment and Conservation, 2013; de Tores et al., 2007).

The quokka is currently listed as vulnerable under national conservation legislation and is recognised as a threatened species under both state and commonwealth frameworks (Department of Biodiversity, Conservation and Attractions, 2020). While Rottnest Island supports the best-known and largest quokka population, mainland quokkas face much greater pressure because they rely on dense, connected vegetation for shelter, feeding, and protection from predators (Hayward, de Tores & Banks, 2005; Department of Biodiversity, Conservation and Attractions, 2020).

One of the major causes of quokka decline has been predation by introduced species, particularly the European red fox, which arrived in south-western Western Australia in the 1930s (Hayward et al., 2005; de Tores et al., 2007). Fox predation has contributed to the collapse of mainland quokka metapopulations, making it harder for quokkas to move safely between habitat patches and recolonise areas where local populations have disappeared (Hayward et al., 2005). Feral cats are also considered a threat, especially to young quokkas and small, isolated populations already under pressure (Department of Environment and Conservation, 2013).

Habitat loss and degradation are also major threats. Quokkas depend on dense vegetation, swamp systems, riparian zones, and complex forest structure for food, shelter, and predator refuge (Hayward et al., 2005; Bain, Wayne & Bencini, 2016). In the northern jarrah forest, research found that quokkas were largely restricted to patchy Agonis swamps, where dense cover and suitable post-fire vegetation provided both dietary resources and protection from predators (Hayward et al., 2005). In southern forest habitats, quokkas appear to benefit from complex vegetation structure and fine-scale habitat patchiness, especially where unburnt refuge areas remain after fire (Bain et al., 2016).

Other pressures include feral pig damage, altered fire regimes, disease risk, Phytophthora dieback, drying wetland habitats, and climate change (Department of Biodiversity, Conservation and Attractions, 2020). Climate change is particularly concerning because mainland quokkas are closely associated with wetter habitats in south-western Australia. Model

ling suggests that future drying could further reduce suitable habitat and contribute to additional range contraction (Gibson et al., 2010).

Conservation efforts focus on protecting the populations that remain. Current and recommended actions include regular surveys, long-term population monitoring, fox and feral cat control, feral pig control, habitat protection, fire management, disease monitoring, community education, and, where necessary, translocation or captive breeding (Department of Environment and Conservation, 2013; Department of Biodiversity, Conservation and Attractions, 2020). Western Australia’s Western Shield program also supports quokka recovery by managing introduced predators across key conservation areas (Department of Biodiversity, Conservation and Attractions, 2020).

Protecting quokkas means protecting more than just the famous population on Rottnest Island. It means safeguarding the smaller and more fragile mainland populations that still survive in the forests, wetlands, and the coastal habitats of southwestern Western Australia.