Threatened Species Strategy – Year 3 Priority Species Scorecard (2018)

Western Ringtail Possum occidentalis

Key Findings Western Ringtail Possums are dependent on high quality forage from myrtaceous tree species. Historic and ongoing declines are due to habitat loss and fragmentation, changed fire regimes, and predation by cats, foxes and dogs in some areas. Declines are likely to continue as climatic conditions become drier and warmer, affecting food supply, fire regimes and possum behaviour. Conservation actions have included control of introduced predators, reducing impacts from timber harvesting, prescribed controlled burning and awareness-raising events to minimise the impact of human activities on Western Ringtail Possums where the species co- exists near people. Photo: Adrian Wayne

Significant trajectory change from 2005-15 to 2015-18? Yes, decline ongoing but at a slower rate.

Priority future actions • Effetcively manage threats from fire, feral predators and weeds at selected important sites. • Restore connectivity and habitat in selected important areas. • Implement forest practices to minimise declines in foresty areas.

Full assessment information

Background information 2018 population trajectory assessment

1. and 8. Expert elicitation for population trends 2. Conservation history and prospects 9. Immediate priorities from 2019 3. Past and current trends 10. Contributors 4. Key threats 11. Legislative documents 5. Past and current management 12. References 6. Support from the Australian Government 13. Citation 7. Measuring progress towards conservation

The primary purpose of this scorecard is to assess progress against the year three targets outlined in the Australian Government’s Threatened Species Strategy, including estimating the change in population trajectory of 20 species. It has been prepared by experts from the National Environmental Science Program’s Threatened Species Recovery Hub, with input from a number of taxon experts, a range of stakeholders and staff from the Office of the Threatened Species Commissioner, for the information of the Australian Government and is non-statutory. It has been informed by statutory planning documents that guide recovery of the species, such as Recovery Plans and/or Conservation Advices (see Section 11). The descriptive information in the scorecard is drawn from the summaries of (Woinarski et al. 2014; Burbidge and Woinarski 2017; DPaW 2017; TSSC 2018) and references therein. The background information aims to provide context for estimation of progress in research and management (Section 7) and estimation of population size and trajectories (Section 8).

1 Information current to December 2018 Threatened Species Strategy – Year 3 Priority Species Scorecard (2018)

1. Conservation status and taxonomy

Taxonomy: Conservation 2018 No subspecies are recognised. Pseudocheirus occidentalis status has been synonymised with the P. peregrinus of eastern Australia by some authors, or EPBC proposed as a subspecies of P. peregrinus. However, its distinctiveness is widely accepted, despite no published WA Critically Endangered analysis of comparative morphology or molecular profiles. 2. Conservation history and prospects The Western Ringtail Possum is endemic to the southwest of . It is arboreal, and the smallest (c. 1.3 kg) herbivore, preferring myrtaceous species such as coastal peppermint . The possum is sensitive to variation in the nutritional quality of its food source, with adult condition and successful recruitment tied to the availability of higher quality forage. It rests in self-made dreys or tree hollows, but also in hollow logs, shrubs and grass trees near or on the ground, if introduced predators are controlled and fires are infrequent.

Sub-fossil evidence indicates a pre-historic distribution across south-west WA from just south of to the southern edge of the Nullarbor Plan. At the time of European settlement, the Western Ringtail Possum occurred from north of Perth to east of Albany. The possum had disappeared from at least 80% of the pre-European range by 1980. After 1980, the distribution and population size of the Western Ringtail Possum continues to decline; the possum mostly persists now in three zones: the Swan Coastal Plain zone, Southern Forest zone and the South Coast zone. Some populations exist outside these areas, but they are relatively much smaller.

The 2018 Conservation Advice presents evidence (from Barbara Jones) of a history of declines from the 1990s, from a total population of at least 40,000 possums (in the 1990s), to 18,000 possums in 2006, and then to 3400 possums in 2015, indicating a 80% decline in the ten years to 2015. Of note, the Upper Warren area (in the Southern Forest zone) which harboured the largest sub-population of Western Ringtail Possums in the 1990s (at least 32,000), experienced a decline of over 95% between 1998 and 2009. (However, note that more recent unpublished work by DBCA suggests the Western Ringtail Possum population may be larger than the figures quoted by B. Jones; whether this affects the estimates for population decline is unclear; DBCA, pers. comm).

The Western Ringtail Possum population is fragmented, still declining, and the declines are expected to continue, as the climate continues to dry and warm, the other threats of clearing habitat for development, introduced predators and fire are still present, and the longer-term effects of fragmentation on population viability play out. For example, a population viability analysis for a small portion of the sub-population on the Swan Coastal Plain found that the probability of local extinction in the next 20 years was 92%.

2 Information current to December 2018 Threatened Species Strategy – Year 3 Priority Species Scorecard (2018)

Western Ringtail Possums (mostly displaced or rehabilitated individuals) have been reintroduced to many sites, with only some of these release sites approved by the Department of Parks and Wildlife. Translocated populations have persisted at only a handful of these release sites, including Perup Sanctuary and Yalgorup NP.

3. Past and current trends Estimates of the population size of Western Ringtail Possums are hampered by the difficulties of censusing the species. A range of different survey techniques are used (e.g. spotlighting, drey searches, scat counts, distance sampling), which further compounds the difficulties of combining information across sites, and sometimes also through time (if methods change). Nevertheless, long-term monitoring data and expert opinion suggest that the post-1980 declines have been very severe: The nomination information that forms the basis for the 2018 Conservation Advice presents a case for a decline from at least 40,000 possums in the 1990s, to 18,000 possums in 2006, and then to 3400 possums in 2015 (making an 80% decline between 2006 and 2015) (B. Jones, in the species nomination form). Recent unpublished work by DBCA suggests the Western Ringtail Possum population may be larger than the figures quoted by B. Jones in the species nomination form, but it is unclear whether this would have a material impact on the estimate for rate of decline (if all population estimates are shifted up, the rate of decline could remain similar). The 2012 Mammal Action Plan suggested a total population size of less than 8000.

Of note, the Upper Warren area (in the Southern Forest zone) which harboured the largest sub- population of Western Ringtail Possums in the 1990s (of at least 32,000 possums), experienced a decline of over 95% between 1998 and 2009. Western Ringtail Possums on the Swan Coastal Plain have also experienced a range contraction since the 1990s, mainly due to habitat fragmentation and climate change impacts on their habitat, with monitored populations showing declines of 20-80%. The population trend of the South Coast western ringtails is less clear. Since the steepest decline in the Upper Warren occurred prior to 2009, it is likely that the overall decline in the past three years (2015- 18) is less severe. However, given the ongoing nature of most threats to the Western Ringtail Possum, an ongoing decline is expected.

The 2017 Recovery Plan gives a population of in an Area of Occupancy of less than 800 km2, and note it is likely an overestimate because of recent declines. The 2012 Mammal Action Plan and the 2018 Conservation Advice estimated an area of occupancy of less than 500 km2. These figures are rubbery, partly because of the rapidity of the population decline.

Monitoring (existing programs): • Targeted regional surveys conducted at Southern Forest zone • Numerous small-scale surveys conducted at development sites on the Swan Coastal Plain zone • Community spotlighting surveys conducted in Busselton, Bunbury and Albany • Opportunistic sightings reported for the species’ entire distribution but particularly near urban/suburban areas • Long-term spotlighting (responses to timber harvesting and regional trends (DBCA, 1994- ongoing in Kingstone, Upper Warren Region)

3 Information current to December 2018 Threatened Species Strategy – Year 3 Priority Species Scorecard (2018)

• Spotlighting (as part of Monitoring (DBCA, 2000-ongoing in Boyicup, Moopinup, and Warrup Upper Warren) • Spotlighting (translocation monitoring) (DBCA, 2000-current in Perup Sanctuary, Upper Warren) • Spotlighting (responses to burning and harvesting for translocation) (DBCA, 2016-current in Alco Corbal, Upper Warren) • Long term spotlighting (DBCA, 1988-ongoing in core habitat in Tuart Forest NP, DBCA) • Spotlight (response to pine harvesting and regeneration back to native forests (DBCA, 2001- current, Tuart Forest NP) Population trends: Tables 1 and 2 summarise the overall trend and status of the Western Ringtail Possum. The information in these tables is derived from the 2012 Mammal Action Plan, the 2018 Conservation Advice, and the 2017 Recovery Plan, with some amendments made by contributing experts based on new information.

Table 1. Summary of the available information on Western Ringtail Possum distribution and population size, and (where possible) trend estimates between 2015 and 2018 for each parameter.

Population Confidence in Published baseline 2015 Estimate 2018 Estimate parameters estimates

WILD* Extent of Occurrence 40 400 km2 40,000 n/a Low Area of Occupancy <500 km2 <500 <500 Low (Burbidge and Mammal Action Woinarski 2017; Dates of records and Plan. IUCN guidelines TSSC 2018). (TSSC 2018) methods used used for records DBCA note that AoO from 1993 – 2012 increases with recent survey effort No. mature individuals <8000 3400 <3400 Low 5 5 No. of subpopulations 3 (3 management (3 management High zones in the RP) zones in the RP) No. of locations 1 1 1 High Medium (as per Generation time 3 n/a n/a MAP) *Including translocations.

4 Information current to December 2018 Threatened Species Strategy – Year 3 Priority Species Scorecard (2018)

Table 2. Estimated recent (2005-2015) and current (2015-2018) population trends for the Western Ringtail Possum. These figures are based on estimates for the period 2003-2015 provided by B. Jones in the species nomination form of the 2018 Conservation Advice. Recent, unpublished work by DBCA suggests higher figures, but these are not yet available (DBCA, pers. comm.).

Est. % of Confidence Confidence Est. % of total 2005- 2015- Sub- in in total pop’n 2015 2018 Details population 2005-2015 2015-2018 pop’n (pre- trend trend trend trend (2018) 2015)

Swan Coastal Recovery Plan notes that Plain monitored populations have (comprising 73% showed declines of 20-80% since Southern the 1990s. (assume Swan, and 73% Medium- Medium- B. Jones (in 2018 Conservation same % Cape to Cape, (2500) Low Low Advice) estimates a 60-65% of B. Jones in as for decline in part of this zone the 2018 2015) between 2003-2015, with a Conservation population of 6800 in 2003, 5800 Advice) in 2006 and 2500 in 2015

12% The only zone with long-term (400) Southern quantitative data. Most of this Forest zone (this decline occurred by 2002, or (comprising zone 12% 2008 at the latest. I.e. BEFORE 2005 (A. Wayne, in 2018 Upper Warren had (assume Conservation Advice). and Forest about High Medium same % rivers of B. 80% of B. Jones (in 2018 Conservation as for Jones in the the Advice) estimates that less than 2015) 2018 overall 1% of the 2000-02 population Conservation pop’n in persisted by 2012-15, with a population of 32,600 in 2003, Advice) the 11,500 in 2006 and 300 in 2015. 1990s)

15% Recovery Plan states no strong evidence for decline in this zone. (assume South Coast 15% B. Jones (in 2018 Conservation High Medium same % MZ (500) Advice) estimates a population as for around Albany of 700 in 2003, 2015) 650 in 2006 and 200 in 2015.

Whole 100% B. Jones estimates a 90% decline High High 100% population (3400) between 2003-15

KEY: Improving Stable Deteriorating Unknown Confidence Description High Trend documented Medium Trend considered likely based on documentation

? Low Trend suspected but evidence indirect or equivocal

5 Information current to December 2018 Threatened Species Strategy – Year 3 Priority Species Scorecard (2018)

4. Key threats The threats listed here are derived from the latest Conservation Advice (TSSC 2018) and Recovery Plan (DPaW 2017). The Western Ringtail Possum is affected by a large number of interacting threats, of which the severity varies among populations. These key threats include:

Climate change Western Ringtail Possums are among the species most likely to be impacted by recent and predicted climate change in the south-west. Adult survival and juvenile recruitment are reduced when food quality declines. A drying and warming climate affects the nutritional quality of their food because less new growth is produced, and the older leaves contain more accumulated toxins, have less water and often less nitrogen than the younger leaves. Increasing CO2 levels in the air also contribute to reduced nitrogen content, and increased fibre and toxin content in foliage. Over the past 30 years, the average annual rainfall had decreased by 20% and western ringtails are contracting to the most mesic remnants of their former range. The declining rainfall is contributing (along with increased residential and agricultural demands) to lower groundwater levels and recharge rates, which accentuates impacts on foliage nutritional quality.

The warming climate may be exacerbating outbreaks of insects that affect foliage availability and quality. For example, warm winters can lead to outbreaks of gumleaf skeletoniser (Uraba lugens), a moth that can substantially reduce tree leaf area across extensive areas for months or years.

As well as affecting the nutritional quality of foliage, increasing temperatures also affect western ringtails directly, as they easily overheat. Hot weather also tends to cause them to move towards the ground, which exposes them to increased predation risk

Climate change may also lead to changing fire regimes (specifically an increase in the frequency and/or intensity of fires) which are likely to accentuate declines in Western Ringtail Possums.

Climate change is expected to be more marked in the Southern Forest zone than the other two zones.

Habitat loss and fragmentation from urban development Habitat loss and fragmentation has been a major contributor to past Western Ringtail Possum declines; land clearing for agriculture targeted more fertile, productive and mesic land which contained much of the higher quality habitat. Habitat loss and fragmentation as a result of urban development continues to threaten western ringtails (although Western Ringtail Possums do persist in some urban areas by utilising garden trees and other vegetation). Possums depend on midstorey and overstorey vegetation for food, shelter and protection from predators. The possums have poor dispersal capabilities between habitat patches, which means the long-term viability of populations is compromised in small habitat patches with poor connectivity to other habitat.

This threat particularly affects coastal and near-coastal populations of Western Ringtail Possums in the Swan Coastal Plain and the Southern Coast zones.

6 Information current to December 2018 Threatened Species Strategy – Year 3 Priority Species Scorecard (2018)

Habitat loss and fragmentation from timber harvesting In forest habitat Western Ringtail Possums are more abundant in unlogged forests or where logging has been least intense. Logging causes direct and immediate mortality, and also increases predation rates on the Western Ringtail Possum (because of the loss of canopy connectivity, plus the migration of predators into the disturbed site).

Timber harvesting impacts are more relevant to possums in the Southern Forest zone than in the other two zones.

Predation by introduced predators Red foxes (Vulpes vulpes) and feral cats (Felis catus) are major predators of the Western Ringtail Possum, and this is exacerbated when the ground and mid-story is opened up by fire, and when hot weather or fragmentation forces possums closer to the ground. Fragmentation can also lead to increased densities of introduced predators in some situations. Close to urbanised areas, domestic dogs are an additional source of mortality from introduced predators.

Predation is believed to be a greater threat to possums in the Southern Forest zone than in the other two zones.

Fire Possum abundance is higher in areas where fire intensity has been low or in areas that have not burnt for long periods. Fire can directly kill possums as they shelter in dreys and hollows; fire also reduces the density of vegetation, exposing the possums to increased predation, including by introduced predators. Finally, fire can reduce the availability and/or quality of food resources.

Since the 2016 Waroona/Yarloop fires, new prescribed burning regimes have been implemented on all government managed lands in southwest WA, including local government areas containing Western Ringtail Possum populations (e.g. in the Mandurah region). These regimes generally involve six-year rotational burning of 45% of southwest reserves, undertaken in autumn-spring, which is when the possums are breeding. This broadscale, high frequency, seasonal burning in remnant vegetation and reserves impacts on Western Ringtail Possums by affecting food availability and quality, causing direct mortality, amplifying predation risk, and degrading habitat by disadvantaging plant species requiring longer than 6 years to reach maturity.

Fire is believed to be a greater threat to possums in the Southern Forest zone than in the other two zones.

Mortality from vehicle-strike on roads Road-strikes are common for Western Ringtail Possums, and in urbanised areas this can be a serious cause of mortality.

7 Information current to December 2018 Threatened Species Strategy – Year 3 Priority Species Scorecard (2018)

Competition for tree hollows Western Ringtail Possum survivorship has been shown to be negatively associated with high numbers of the sympatric Common Brush-tail Possum (Trichosurus vulpecula). Brushtails are larger, more mobile, more aggressive and have been frequently observed evicting western ringtails from hollows. Other species, such as the European Honeybee (Apis mellifera), Rainbow Lorikeets (Trichoglossus haematodus) and Little Corellas (Cacatua sanguinea) may also compete with Western Ringtail Possums for hollows. The severity of this threat varies across populations, and possibly also varies through time. Increases in brushtail possum density can occur in areas where foxes are poison-baited. Competition for hollows is more severe in logged forests, where tree hollows are scarcer.

Tree decline as a result of disease Western Ringtail Possums are obligate folivores, and therefore are susceptible to tree decline, which reduces the quality of habitat and food resources. Phytophthora cinnamomi, Neofusicoccom australe and Armillaria luteobubalina are all pathogens that cause dieback in Western Australian tree species. Myrtle Rust (Puccina psidii s.l.) is part of a group of fungi that infects species in the Myrtaceae. It has not yet reached WA, but if introduced it is likely to have negative impacts on the habitat trees of Western Ringtail Possums.

Disease Western Ringtail Possums can be at greater risk of disease due to human disturbance and exposure to exotic species and pathogens. Cat predation may also expose Western Ringtail Possums to toxoplasmosis infection, although investigations into the disease load of captive and wild populations has revealed only low rates of contagion.

The impacts of the major threats are summarised in Table 3.

Table 3. The major threats facing the Western Ringtail Possum and their associated impact scores. CURRENT THREAT IMPACT Threat Timing Extent Severity

1. Climate change (drought and reduced rainfall) Continuing/ongoing >90% of range 50-100%

2. Residential and commercial development Continuing/ongoing 50-90% of range 30-50% (Habitat loss and fragmentation)

3. Agro-forestry (Habitat loss and fragmentation) Continuing/ongoing 1-50% of range 20-29%

4. Vulpes vulpes Continuing/ongoing >90% of range 20-29%

5. Cats Felis catus Continuing/ongoing >90% of range 20-29%

6. Increase in fire frequency/intensity Continuing/ongoing >90% of range 20-29% Timing: continuing/ongoing; near future: any occurrence probable within one generation (includes former threat no longer causing impact but could readily recur); distant future: any occurrence likely to be further than one generation into the future (includes former threat no longer causing impact and unlikely to recur). Extent: <1% of range; 1-50%; 50-90%; >90%. Severity: (within three generations or 10 years, whichever is longer) Causing no decline; Negligible declines (<1%); Not negligible but <20%; 20-29%; 30-49%; 50-100%; Causing/could cause order of magnitude fluctuations.

8 Information current to December 2018 Threatened Species Strategy – Year 3 Priority Species Scorecard (2018)

5. Past and current management Recent and current management actions thought to support the conservation of the Western Ringtail Possum are summarised in Table 4. The information is a collation of material provided by contributors. A Recovery Plan (2017) and Conservation Advice (2018) are in place, guiding recovery action (see Section 11). Table 4. Management actions that support the conservation of the Western Ringtail Possum.

Est. % Contributors and Action Location Timing pop’n partners

Public land (reserves and Fox and cat control by broad-scale poison-baiting DBCA; State forestry), Swan 1996-2018 20-30% (as part of Western Shield)? Forestry Coastal/Southern Forest/South coast

DBCA, Australian Eradicat bait trials in southern Warren Region 2015-2018 Govt,

Statutory and local government planning Local, State, approvals place conditions on development; Private land 50% Australian including relocation of possums governments

Revegetation of ex-pasture land/ habitat creation (Majority of sites yet to achieve habitat Swan Coastal, City DBCA (various 2006- characteristics suitable for WRP occupancy. of Busselton, <1% development current Monitoring over the next decade will be required Capel Shire offsets) to assess effectiveness)

Nature Conservation Margaret River Managing Bushland for Wildlife Program 2017-2018 Margaret River region Region (OTSC). DBCA

Guidelines developed to reduce impacts of Public land prescribed burning on possum habitat (e.g. by DBCA; State (reserves and Since 2016 32% using marginal mowing and controlling flammable Forestry forestry) weeds instead of burning)

Modified logging practices under the Forest Management Plan 2014-2023 for timber State Forest and DBCA; State harvesting in possum habitat. E.g. increasing area Since 2014 11% Timber reserves Forestry of mature forest in the fauna habitat zone network; mapping areas of possum habitat

Monitoring core areas of the Albany urban matrix, OHCG, UWA, City reduction of educational material to raise of Albany, Albany awareness in broader community; engage with community groups, volunteer and community groups DBCA

Greater understanding of WRP occurrence and Bronte Van Helden habitat use within Albany urban matrix (Hons Albany 2015-2018 (UWA), DBCA Thesis) and now PhD project

9 Information current to December 2018 Threatened Species Strategy – Year 3 Priority Species Scorecard (2018)

Creation of environmental planning tool to WALGA, DBCA, improve data available for local government land Albany, WA LGAs 2013-2016 DPHL, CoA use planning decisions

City of Mandurah, Swan Coast, City Main Roads Dept., Rope bridge trials (varying success – limited use to 2014, of Busselton, City SW Catchment active use) 2018 of Bunbury, Council, Water Corporation, DBCA

Management and engagement with wildlife rehabilitators and support organisations (Multiple organisations are undertaking media and events Swan to raise the awareness of the WRP. The WRP Coastal/Southern Ongoing DBCA recovery team are working towards a Forest/South collaborative and coordinated approach to share Coast awareness raising activities, information and products.)

NESP Citizen Science Project. Online surveys to encourage south west residents to share their Rochelle Steven backyard knowledge on the WRP (learn more Albany, Bunbury 2018 (NESP TSR Hub) about WRP, community attitudes, and how best to protect them).

6. Actions undertaken or supported by the Australian Government resulting from inclusion in the Threatened Species Strategy

The Australian Government has supported the following three projects may benefit the Western Ringtail Possum:

i. The “Applying best practice feral cat and fox baiting in WA” partnership project ($1.7 million support from the Australian Government). This project may have had minor benefits for the possum, but it was mostly implemented outside of the possum distribution. ii. A 20 Million Trees Round 3 Project “Biodiversity Urban Corridors” provided $96,500 to the City of Albany to revegetate and complement ongoing conservation efforts for Lake Seppings. iii. The Numbat Protection Dog project to develop the use of cat detector dogs to protect the last remaining wild populations of Numbat may also provide indirect benefits to the Western Ringtail Possum, in the longer term. iv. The National Landcare program provided $150,000 to the Foundation for Australia’s Most Endangered Species Limited in 2016-17.

10 Information current to December 2018 Threatened Species Strategy – Year 3 Priority Species Scorecard (2018)

7. Measuring progress towards conservation Table 5. Progress towards management understanding and management implementation for each of the major threats affecting the Western Ringtail Possum in 2015 and 2018, using the progress framework developed by Garnett et al. 2018.

PROGRESS IN MANAGING THREATS

Threat Year Understanding of how to manage threat Extent to which threat being managed

2.Research has provided strong direction on how 1. Climate change 2015 0.No management to manage threat (drought and 2.Research has provided strong direction on how reduced rainfall) 2018 0.No management to manage threat 2. Residential and 3. Solutions being trialled but work only initiated 2015 1.Management limited to trials commercial recently development 3. Solutions being trialled but work only initiated 2.Work has been initiated to roll out solutions (Habitat loss and 2018 recently where threat applies across the taxon’s range fragmentation) 3. Solutions being trialled but work only initiated 2.Work has been initiated to roll out solutions 2015 3. Agro-forestry recently where threat applies across the taxon’s range (Habitat loss and 3. Solutions being trialled but work only initiated 2.Work has been initiated to roll out solutions fragmentation) 2018 recently where threat applies across the taxon’s range 5. Trial management is providing clear evidence 4. Solutions are enabling achievement but only 2015 4. Red fox Vulpes that it can deliver objectives with continued conservation intervention vulpes 5. Trial management is providing clear evidence 4. Solutions are enabling achievement but only 2018 that it can deliver objectives with continued conservation intervention 3. Solutions being trialled but work only initiated 2.Work has been initiated to roll out solutions 2015 recently where threat applies across the taxon’s range 5. Cats Felis catus 3. Solutions being trialled but work only initiated 2.Work has been initiated to roll out solutions 2018 recently where threat applies across the taxon’s range 2. Research has provided strong direction on how 3. Solutions have been adopted but too early to 2015 6. Increase in fire to manage threat demonstrate success frequency/intensity 2. Research has provided strong direction on how 3. Solutions have been adopted but too early to 2018 to manage threat demonstrate success > Green shading indicates an improvement in our understanding or management of threats between years 2015 and 2018, while red shading indicates deterioration in our understanding or management of threats.

KEY Score Understanding of how to manage threat Extent to which threat is being managed 0 No knowledge and no research No management Research being undertaken or completed but limited 1 Management limited to trials understanding on how to manage threat Research has provided strong direction on how to manage Work has been initiated to roll out solutions where threat 2 threat applies across the taxon’s range Solutions have been adopted but too early to demonstrate 3 Solutions being trialled but work only initiated recently success Trial management under way but not yet clear evidence Solutions are enabling achievement but only with 4 that it can deliver objectives continued conservation intervention Trial management is providing clear evidence that it can Good evidence available that solutions are enabling 5 deliver objectives achievement with little or no conservation intervention Research complete and being applied OR ongoing research 6 The threat no longer needs management associated with adaptive management of threat

11 Information current to December 2018 Threatened Species Strategy – Year 3 Priority Species Scorecard (2018)

8. Expert elicitation for population trends An expert elicitation process was undertaken to assess population trends for the period 2005-2015 and post-2015 under the following management scenarios. Please note that differences between Management Scenarios 2 and 3 (Fig. 1) are difficult to attribute, as it can be difficult to determine whether actions undertaken after 2015 were influenced by the Threatened Species Strategy or were independent of it (see Summary Report for details of methods). Management Scenario 1 (red line): no conservation management undertaken since 2015, and no new actions implemented.

• No control of foxes and cats • Fire management absent, or soley focussed on hazard reduction • No controls on groundwater depletion • No controls on urban development • No controls on forestry practices • No action on climate change Management Scenario 2 (blue line): continuation of existing conservation management (i.e. actions undertaken before implementation of the Threatened Species Strategy or independent of the Threatened Species Strategy).

• Broad-scale baiting of foxes and cats • Fire management focussed on hazard reduction, but with some modification in WRP habitat • Limited control on groundwater depletion • Regulated control on urban development • Regulated control on foresty practices • No action on climate change Management Scenario 3 (green line): continuation of existing management, augmented by support mobilised by the Australian Government under the Threatened Species Strategy.

• Broad-scale baiting of foxes and cats • Fire management focussed on hazard reduction, but with some modification in WRP habitat • Limited control on groundwater depletion • Regulated control on urban development • Regulated control on foresty practices • No action on climate change

Overall estimated population trajectories subject to management scenarios considered The Western Ringtail Possum is currently being managed under Scenario 3 (green line). Note that the contributions associated with the TSS are small, and consequently unlikely to influence this species much in terms of improving it’s population trajectory (and thus the blue line is obscured).

12 Information current to December 2018 Threatened Species Strategy – Year 3 Priority Species Scorecard (2018)

Figure 1. Estimated relative percentage change in population under each of the management scenarios described above. Data derived from 6 expert assessments of Western Ringtail Possum expected response to management, using four-step elicitation and the IDEA protocol (Hemming et al. 2017), where experts are asked to provide best estimates, lowest and highest plausible estimates, and an associated level of confidence. The dashed line represents the baseline value (i.e. as at 2015, standardised to 100). Values above this line indicate a relative increase in population size, while values below this line indicate a relative decrease in population size. Shading indicates confidence bounds (i.e. the lowest and highest plausible estimates).

Population size projections based on expert elicitation are extended here to 2025, 2035 and 2045 (i.e. 10, 20 and 30 years after the establishment of the Threatened Species Strategy) on the grounds that some priority conservation management actions may take many years to achieve substantial conservation outcomes. However, we note also that there will be greater uncertainty around estimates of population size into the more distant future because, for example, novel threats may affect the species, managers may develop new and more efficient conservation options, and the impacts of climate change may be challenging to predict.

13 Information current to December 2018 Threatened Species Strategy – Year 3 Priority Species Scorecard (2018)

Improved trajectory (Threatened Species Strategy Year 3 target): The primary purpose of this scorecard is to assess progress against achieving the year three targets outlined in the Australian Government’s Threatened Species Strategy, i.e. a demonstrated improved trajectory for at least half of the priority species (10 birds and 10 ). To assess this, we first use the expert-derived trend between 2005-15 (i.e. 10 years prior to implementation of the TSS) as a baseline for assessing whether there has been an improvement in trajectory in the time since implementation of the TSS (i.e. 2015-18). Table 6 below summarises this information, where negative values indicate a declining population, and positive values indicate an increasing population. We used Wilcoxon match-paired tests to compare trajectories for these two periods; a significant result (probability <0.05) indicates that there was a high concordance amongst experts that their trajectory estimates for 2005-15 were different to their estimates for 2015-18. Table 6. A comparison of the relative annual percentage population change for the periods 2005- 2015 and 2015-2018.

Post-TSS Year 3 Pre-TSS trend Significant concordance among trend target (2005-2015) elicitors? (2015-2018) met? Although this species is undergoing Annual continuing decline, elcitors consistently percentage -37.1 -4.41 considered the rate of decline was less population  steep in the 2015-18 period than the 2005- change 15 period

The TSS has mobilised support through 20 Million Trees and Green Army for habitat restoration activities, but at very small scales. The TSS support for feral cat and fox control is not expected to contribute directly to the recovery of this species. Additional actions that could improve trajectory The potential impact of carrying out specific additional conservation measures on the population trajectory of the Western Ringtail Possum was also evaluated through expert elicitation. Additional actions that could further improve the population trajectory of the Western Ringtail Possum include:

• Broad-scale and effective baiting of foxes and cats • Fire management that focuses primarily on conservation needs of Western Ringtail Possums in possum habitat • Population genetics are used to guide options for translocation • Translocation program attached to habitat management (of fire, weeds and feral ) • Management of groundwater depletion • Strategic and effective control on urban development to minimise loss of connectivity, mortality from roads, mortality from domestic cats and dogs • Forestry managed so existing high quality possum habitat is excluded from logging, and potential high quality possum habitat is also protected to provide future habitat • Mitigation of climate change

14 Information current to December 2018 Threatened Species Strategy – Year 3 Priority Species Scorecard (2018)

9. Immediate priorities from 2019 The Western Ringtail Possum Recovery Plan was updated and adopted in 2017, which was closely followed by the re-establishment of the Western Ringtail Possum Recovery Team. The recovery team includes representatives from the three management zones (Swan Coastal Plain, Southern Forest and South Coast). Conservation actions and planning have been occurring in the Swan Coastal Plain and Southern Forest management zones consistently for a lengthy period of time associated with key processes such as development and silvicultural practices. Conservation actions and planning in the South Coast Management Zone has largely been ad hoc and opportunistic until 2008, where NRM funding and post graduate studies have placed an increased focus and effort on surveying and assessment of the status of the south coast population. This effort is continuing to build an understanding of the south coast population in urban environments but needs to be expanded to provide a broader content. Identification of these priorities in this document is for information and is non-statutory. For statutory conservation planning documents, such as Recovery Plans or Conservation Advices, please see Section 11. Data collection: • Design and implement monitoring program across the existing distribution of the Western Ringtail Possum, that focuses on measuring outcomes of conservation management • Develop habitat management plan for the species across its range, based on  Spatial distribution of current and future habitat, including as affected by climate change  Population genetics study to inform metapopulation management (including with translocations) • Using information from the habitat management plan, carry out regional strategic assessment to minimise impacts of urban development across the species’ distribution, and optimise approach to development applications and approvals Management actions: • Manage threats from fire, feral predators, weeds, in all existing possum habitat identified as important for the long-term viability of the species • Restore connectivity where possible, and restore habitat in areas that will contribute to that long term viability • Implement forest practices to minimise declines in foresty areas (eg. to identify and exclude high quality current and future possum habitat from logging).

10. Contributors Sarah Legge, John Woinarski, Stephen Garnett, Hayley Geyle (NESP TSR Hub); Deon Utber, Adrian Wayne, Sarah Comer, Kim Williams, Mark Virgo and Manda Page (WA DBCA); Andrew Burbidge; Peter Menkhorst; Nicholas MacGregor.

15 Information current to December 2018 Threatened Species Strategy – Year 3 Priority Species Scorecard (2018)

11. Legislative documents SPRAT profile: http://www.environment.gov.au/cgi- bin/sprat/public/publicspecies.pl?taxon_id=25911

Department of Parks and Wildlife (2017). Western Ringtail Possum (Pseudocheirus occidentalis) Recovery Plan. Wildlife Management Program No. 58. Department of Parks and Wildlife, Perth, WA. Available from: http://www.environment.gov.au/biodiversity/threatened/publications/recovery/western-ringtail- possum-recovery-plan. In effect under the EPBC Act from 16-Aug-2017 as Pseudocheirus occidentalis Threatened Species Scientific Committee (2018). Conservation Advice Pseudocheirus occidentalis Western Ringtail Possum. Canberra: Department of the Environment and Energy. Available from: http://www.environment.gov.au/biodiversity/threatened/species/pubs/25911-conservation-advice- 11052018.pdf. In effect under the EPBC Act from 11-May-2018

12. References Burbidge, A. and Woinarski, J. (2017). Pseudocheirus occidentalis. The IUCN Red List of Threatened Species 2017: e.T18492A21963100. http://dx.doi.org/10.2305/IUCN.UK.2017- 3.RLTS.T18492A21963100.en. . DPaW (2017). Western Ringtail Possum (Pseudocheirus occidentalis) Recovery Plan. Wildlife Management Program No. 58. (Department of Parks and Wildlife: Perth, WA.) Garnett, S.T., Butchart, S.H.M., Baker, G.B., Bayraktarov, E., Buchanan, K.L., Burbidge, A.A., Chauvenet, A.L.M., Christidis, L., Ehmke, G., Grace, M., Hoccom, D.G., Legge, S.M., Leiper, I., Lindenmayer, D.B., Loyn, R.H., Maron, M., McDonald, P., Menkhorst, P., Possingham, H.P., Radford, J., Reside, A.E., Watson, D.M., Watson, J.E.M., Wintle, B., Woinarski, J.C.Z., and Geyle, H.M. (2018) Metrics of progress in the understanding and management of threats to Australian Birds. Conservation Biology https://doi.org/10.1111/cobi.13220. Hemming, V., Burgman, M.A., Hanea, A.M., McBride, M.F., and Wintle B.C. (2017) A practical guide to structured expert elicitation using the IDEA protocol. Methods in Ecology and Evolution, 9, 169- 180. TSSC (2018). Pseudocheirus occidentalis (Western Ringtail Possum) Conservation Advice. (Department of the Environment and Energy: Canberra.) Woinarski, J. C. Z., Burbidge, A. A., and Harrison, P. L. (2014). 'The Action Plan for Australian Mammals 2012.' (CSIRO Publishing: Melbourne.)

13. Citation Please cite this document as:

National Environmental Science Program Threatened Species Research Hub (2019) Threatened Species Strategy Year 3 Scorecard – Western Ringtail Possum. Australian Government, Canberra. Available from: http://www.environment.gov.au/biodiversity/threatened/species/20- mammals-by-2020/western-ringtail-possum

16 Information current to December 2018