The Quokka is evaluated as Vulnerable B2ab(i,ii,iii,iv,v) because its area of occupancy (AOO) is less than 2,000 km², it occurs at fewer than 10 locations, and there is an inferred and projected continuing decline in population size due to the loss of small, isolated subpopulations, and ongoing threats posed by the drying climate, fire and predation by invasive species: the Red Fox Vulpes vulpes, feral Cat Felis catus and Pig Sus scrofa. Fragmentation of subpopulations is increased by the cumulative impacts of fire and predation by Red Foxes, which increases the distance between occupied habitat patches, restricts quokkas to patches of dense vegetation and inhibits dispersal between patches. Habitat quality is being affected by feral Pigs. Many surviving subpopulations may therefore not be viable over the long term, and the original metapopulation structure has collapsed. Significant projected loss of extent of occurrence (EOO) and area of occupancy (AOO) due to climate change, mainly a continuing reduction in winter rainfall, has been predicted.

The Quokka is listed as Vulnerable under national environmental law, and Vulnerable under Western Australian law.

The Quokka is endemic to south-western Australia, including Rottnest (17 km²) and Bald (8 km²) Islands and, formerly, Breaksea Island (1 km², Abbott 2006; Burbidge and Abbott 2017). It was originally distributed from Moore River, 100 km north of Perth, through the higher rainfall part of the south-west, east along the south coast to at least the Green Range, 55 km north-east of Albany. Fossil deposits and historical records suggest that the Quokka originally occupied an area of approximately 41,200 km² in the south-western corner of Australia (de Tores et al. 2007).

Historical literature has shown that they were widespread and abundant when Europeans colonised the region in 1829, but a noticeable and dramatic decline occurred over the following century (Hayward 2002). This can be attributed mainly to the arrival of the Red Fox in the 1930s (Hayward et al. 2005a) and land clearing. There was another major contraction in the period 1980 to 1992, the cause of which is unknown, but it could be related to habitat deterioration, fox predation and declining winter rainfall. Overall the range has contracted southwards with the northernmost records now in the Darling Range immediately south-east of Perth. The extent of occurrence (EOO) was estimated as ca 17,800 km² by de Tores et al. (2007), but our calculation, using records since 2012 and including Rottnest Island, suggests it is 66,000 km². It persists in several healthy subpopulations on the south coast: on Bald Island and between Two Peoples Bay Nature Reserve and Cheyne Beach. In addition there is an isolated south coast subpopulation in Stirling Range National Park. Quokkas are thought to be now absent from the Swan Coastal Plain, except for a small subpopulation at Muddy Lakes, near Bunbury (Sinclair and Hyder 2009). This subpopulation persists and is estimated to be <10 individuals. An interagency working group is aiming to solve some of the complex ex tenure and competing land-use issues such as mosquito control, and to expand the reserve by acquiring adjoining private property wetland lands. The site is fox baited monthly (K. Williams pers. comm. 2024).

Remaining subpopulations throughout much of the current range are small and often isolated. In the northern jarrah forest, subpopulations are severely fragmented because of discontinuous suitable habitat that is affected by clearing for mining, the drying climate and inappropriate fire regimes. Predation by invasive species also limit gene flow between mainland subpopulations. The southern forest and south coast, between Nannup and Cheynes Beach, now supports the most extensive remaining quokka subpopulations on the mainland, and the most genetically diverse subpopulation of the species (Spencer et al. 2020). Quokkas in this region, apart from Bald Island and Stirling Range, appear to be operating as a functional metapopulation, with genetic connectivity maintained between spatially discrete habitat patches and reports of frequent localised extinctions and colonisations (Bain et al. 2015, Spencer et al. 2020).

The area of occupancy (AOO) is thought to have been reduced by around 50% over the past century (de Tores et al. 2007) and will decrease further due to bauxite mining, fire and the drying climate. Significant projected loss of extent of occurrence (EOO) and area of occupancy (AOO) due to climate change, mainly a continuing reduction in winter rainfall, has been predicted (Gibson et al. 2010).

There are no robust estimates of overall abundance; de Tores et al. (2008) suggested that there may be ca 3,500-7,000 individuals on the mainland, 1,200-2,000 of which are along the south coast. It is abundant on Rottnest Island (8,000-12,000 individuals; Phillips 2016) and Bald Island (500-2,000; de Tores et al. 2008). Many mainland subpopulations are thought to consist of only a few individuals (Alecs et al. 2003, Sinclair and Morris 1996). The southern forest/south coast subpopulations are the most robust on the mainland but are comprised of small groups of individuals that move between discrete habitat patches in response to synergistic threats such as fire and feral Pigs Sus scofa that modify habitat suitability and introduced predators such as the Red Fox and feral cat that affect movement and survival (Bain et al. 2015, 2019, 2023). Population size has declined substantially since European settlement, and there is an inferred and projected continuing decline in population size due to the loss of small, isolated subpopulations, the drying climate (Gibson et al. 2010), fire (Bain et al. 2023, Povh et al. 2023) and predation by invasive species: the Red Fox Vulpes vulpes (Kinnear et al. 2002), feral Cat Felis catus (Dickman 1996; Abbott 2002, 2008) and Pig Sus scrofa (Dundas 2013). Fragmentation of subpopulations is increased by the cumulative impacts of fire and predation by Red Foxes, which increases the distance between occupied habitat patches, restricts quokkas to patches of dense vegetation and inhibits dispersal between patches. Many surviving subpopulations may therefore not be viable over the long term, and the original metapopulation structure has collapsed.

Quokkas occur as many small, isolated subpopulations, many of which are within State forest subject to multiple use including mining, ecological thinning, firewood collection, prescribed burning and public recreation. Those within national parks are subject to prescribed burning, while Stirling Range National Park has had more wildfires, mostly caused by lightning in a drying climate. In the northern jarrah forest, Quokkas are closely associated with tea-tree Taxandria linearifolia swamps with a mosaic of trees at differing ages as determined by fire (Hayward et al. 2007, de Tores 2008). In the southern jarrah forest, Quokkas occupy a wider variety of forest, woodland and wetland types including Jarrah Eucalyptus marginata, Marri Corymbia calophylla, Karri E. diversicolor and Tingle E. jacksonii or E. guilfoylei, and sedge-dominated riparian habitats (Bain et al. 2015). Family groups exhibit overlapping home ranges that reflect a general non-territoriality. Quokkas require a mosaic of habitat, including recently-burnt and long-unburnt Taxandria stands, vertical vegetation complexity, and low levels of woody debris on the forest floor (Christensen and Kimber 1975, de Tores et al. 2007, Bain et al. 2015). The vegetation in riparian areas that Quokka utilise can senesce over time (generally >25 yrs, but can be much longer), and prescribed fire can be used to regenerate the vegetation. However, careful consideration must be given to planning areas for fire exclusion to provide refuge areas for quokkas to persist post burn. Prescribed burning should maximise the retention of vertical structure of the vegetation and multiple unburnt vegetation patches across >20% of the total burn area to encourage persistence and rapid recolonisation of quokkas (Bain et al. 2016, Povh et al. 2023). Since the collapse of the northern jarrah metapopulation following the arrival of the Red Fox (Vulpes vulpes) in the 1930s, Quokkas have been forced to remain within small, isolated habitat patches because predation inhibits dispersal in areas with sparse understorey (Hayward et al. 2004, 2005a). This is less of an issue in the southern forest where the understorey is dense across much of the landscape, allowing quokkas to more readily evade predators and move greater distances (Bain et al. 2015, 2019). 

de Tores et al. (2004) reviewed Quokka research and conservation to that date. They noted, so far as the northern jarrah forest subpopulations are concerned, that despite six years of fox baiting, Quokka populations in the northern jarrah forest had not shown a pattern of increase (Hayward et al. 2003). However, a recent study has shown limited recovery of subpopulations in the northern jarrah forest after some years of fox baiting (Dundas et al. 2017).

Along the south coast, Quokkas inhabit swamps, riparian areas, incised gullies and dense heaths. On Rottnest Island, they are found in all vegetation types, sheltering in low scrub (Nicholls 1971; Kitchener 1972, 1982). The biology of Rottnest Island Quokkas has been widely studied (Bradshaw 1983). On Bald Island Quokkas are widespread.

Island populations fluctuate, but appear stable over the long term. Predation by invasive species has led to a past decline of mainland populations. Fox control has led to an increase in numbers in some areas. Feral pigs are causing habitat degradation by modifying the vegetation density and/or structure, making these areas unsuitable for Quokkas. Inappropriate fire regimes can lead to habitat degradation, habitat fragmentation and metapopulation disruption. Climate change leading to less rainfall predicted to become severe (Gibson et al. 2010) and will likely negatively impact the long-term suitability of current quokka habitat areas.

A recovery plan is in effect (DEC 2013). It has the following recovery actions:

• Coordinate recovery actions
• Survey and Monitoring
• Improved understanding of threats and effectiveness of mitigation programs
• Management of key populations and habitats
• Translocations and captive breeding as required
• Education and communication.

Conservation of the Quokka is the responsibility of the Western Australian Department of Biodiversity, Conservation and Attractions (DBCA), which also manages most of its habitat, which lies within State forest, national parks and nature reserves, including Bald Island and Rottnest Island, which is a multiple purpose reserve managed according to the Rottnest Island Authority Act 1987. There has been considerable research into the ecology and conservation of the Quokka in the northern jarrah forest and southern forest and ad hoc surveys elsewhere within its range. Guidelines for the management of logging coupes have been developed (Burrows and Liddelow 2005), but logging has now ceased (but replaced by ecological thinning that impacts a smaller footprint but will still impact areas in which Quokkas occur), as have adaptive guidelines for fire management (Burrows et al. 2007). Rottnest Island is managed primarily for recreation by the Rottnest Island Authority, part of DBCA. Regular fox baiting at known mainland Quokka locations is conducted, along with the establishment of new baiting regimes where predation risk is believed to have increased.

Conservation Objectives are:

1.   Maintain Quokka range and relative abundance

2.   Manage subpopulations within multiple-use State forest to minimise impact of forest management practices

3.   Carry out prescribed burning within quokka habitat to maximise shelter and food requirements, in a manner that protects or proactively manages metapopulation function.

4.   Protect island subpopulations.