WA translocation history in general
and for western ringtail possums

The very high tolerance of native fauna in Western Australia to sodium fluoroacetate (1080) seemed to make broad-scale fox baiting effective for the control of introduced predators with only a low risk for natives. Early translocation successes therefore led to extensive use of this management tool and in consequence to a high number of translocations. The Western Shield Predator Control Program covered almost 4 million hectares of conservation estate in WA. The majority of translocations have been to national parks and nature reserves, the so-called conservation estate. No other state or territory has undertaken as many translocations as Western Australia. (Morris et al, 2015)

Translocations were often the response to development pressure in urban areas.
However, the finding that predation by feral cats increased following fox control (mesopredators release) and the lack of long-term success of translocations of western ringtails led to the questioning of translocation as mitigation for that species. In addition, the ensuing reduction of translocation approvals and in consequence reduced contributions from development has now almost stopped translocations of western ringtail possums.

In general, only 24% of translocations to unfenced mainland sites were deemed successful while 32% failed. The remaining 44% are indeterminable or even unreported. (Morris et al, 2015)

The environment department’s Threatened Fauna Arc project, which was funded by the State NRM agencies, mainly translocated into areas that were free from exotic predators and seemed successful for many species but if ringtail translocations to Perup and Karakamia should have been part of this project, the success was questionable.

Of all translocations undertaken in WA only 35% have been judged successful while 39% cannot be determined as success or failure because monitoring was inadequate. The remaining 26% were definite failures. (Morris et al, 2015)
It is however unclear to me after which period of time this judgement can safely be made. Leschenault Peninsula was deemed a success but the population quickly collapsed after monitoring lapsed. It would be interesting to learn in which category (success or failure) those ringtail translocations were included. 

History of western ringtail possum translocations

The following figures are mostly sourced from an FOI request, Questions asked in Parliament and correspondence with the then minister for the environment, David Templeman.

Up to 1990 ringtails – displaced or rehabilitated – were relocated in an ad-hoc fashion either into conservation reserves or by carers where ever they saw fit. The fate of the possums stayed unknown.

The first short, monitored study was conducted in 1991 by the WA museum.  5 radio-collared ringtails were released in Locke Nature Reserve; however 4 were dead within 6 weeks due to fox predation. (De Tores et al, 1998)

The aims of the departmental program were to extent the species range and to establish new populations in secure conservation estate. The first site chosen for these on-going translocations was Leschenault Peninsula, a small area of vegetation floristically and structurally similar to Locke Nature Reserve (Jones et al, 1994a), which had then and still has one of the largest ringtail colonies.

After first releases at the end of September 1991 (8 rehabilitated ringtails) and no recorded deaths more than 3 months later, 19 more animals were released in January 1992. One of them was dead at the end of the month but the death toll stood at only 3 in March.
Later in 1992/93 11 more animals from carers were added to the population that seemed to be establishing well, before in May 1994 the program was extended to also include animals from development sites (10 from Port Geographe). Another 43 animals were provided by carers that year and 22 more in 1995. The wildlife care community was the main source of ringtails for translocation at that time.
In 1995 Leschenault translocations had been deemed successful and a new translocation destination was added – Yalgorup National Park - with initially 26 ringtails (all from Port Geographe development). 

The target for Leschenault was for ‘96-‘98 to increase density progressively. (De Tores et al, 2004) Spotlighting surveys in 1996 resulted in 72 sightings and in 1998 even 100. (De Tores et al, 2005a) More releases were probably not advisable because of this density and Lane Poole Reserve/Keats Forest Block near Dwellingup was instead chosen for translocations in 1996. After releasing 133 animals – again all supplied by carers – a high loss of animals to presumed predation by chuditch, another vulnerable species, stopped this trial in 1999.

In the period 1996 to 2003 9 animals were translocated to Leschenault and 114 to Yalgorup.
However, figures vary between different publications from the same department.

A lack of funding led to a gap of 4 years in monitoring and 2002 spotlight transect  monitoring at Leschenault came up with only 2 sightings. The assessment of Leschenault Peninsula turned from successful to inconclusive and in 2004 it was evident that translocation success has not been demonstrated at any translocation site. (De Tores et al, 2004)

Changes in baiting regime from monthly to a more irregular pattern with several months skipped and the use of fewer bait that were buried even though bait uptake by foxes is known to be reduced when baits are buried were assumed to have led to an increase in fox numbers and as a consequence higher predation. (De Tores et al, 2004)
Other possible causes included predation by cats and/or pythons, competition with brushtail possums, prey switching, drought, unsuitable habitat, and disease. (De Tores et al, 2004, De Tores, 2005) There has never been any proof for any theory though.

However, in the period 2004/2005 translocations to Leschenault were recommenced with the release of 96 animals even though the issues causing the severe decline had not been investigated let alone been addressed in any way. 58 animals went to Yalgorup National Park in the same period.

Research between February 2006 and the end of 2008 finally was set-up to determine which factors limit translocation success for the species and thereby provide direction for future management. 72 ringtails were provided for this translocation research, 3 of those were not released and one was not collared. The number of animals going into the research was thus 68.
After 2 years of research 45 animals had died, 15 went prematurely off air and their fate is unknown and only 8 survived. The animals were not released simultaneously and death occurred after as little as 2 days in the worst case and after 63 weeks in the best case. (Clarke, 2011)
30 of those animals again went to Leschenault which had not recovered from the decline between 1998 and 2002 despite the additional releases in 2004/2005. (De Tores, 2005, Clarke, 2011) At the end of the study, numbers were basically too low for detection. However dietary analysis of python scats confirmed persistence at levels difficult to detect from standard survey techniques. (De Tores, 2009) Researchers could not find them, but pythons obviously still could.
The most convincing theory seems that a number of severely dry years in a row rendered Leschenault unsuitable as ringtail habitat and the animals failed to establish.

Populations within Yalgorup National Park persisted for at least another year and there was an indication that in one location the population was expanding. (De Tores, 2009)

One of the release areas, the 516 hectares called Martin’s tank, was exempt from prescribed burns throughout the study period (De Tores et al, 2004, De Tores, 2005); however, much of the western half was unintentionally burnt shortly after the field work ended.
The devastating fires in early 2016 then probably caused local extinction in the National Park.

In comparison, Kaori Yokochi radio-collared 53 animals for her PhD research and 23 of those had died at the end of her also 2-year study. (Yokochi, 2015) The clear difference was that in the first study the animals were translocated from very good habitat they were familiar with into probably suboptimal, foreign habitat while in the second study the animals stayed in their good habitat and were only monitored.

Translocations to Karakamia Sanctuary, a predator-free enclosure east of Perth owned by the AWC are rarely mentioned in any translocation document.
In August 1995 the first 5 animals from carers were transferred and kept in holding pens. The diet consisted of peppermints and a variety of locally occurring species. Peppermint was gradually reduced over a 2-months period and pens were opened after more than 3 months of acclimatisation. 2 months later 3 of those animals had died but none of those deaths was related to nutritional deficiencies. (AWC, 1996)

In September 2002, 14 ringtails from a development (Cape Care/Ray Village) joined the population. (AWC, 2002) Whether the delayed release protocol was followed again is unknown. As these were the only publications I could find, it came as a surprise to read that in total 42 ringtails were translocated to Karakamia between 1995 and 2002. 
The additional 23 animals came from Busselton wildlife carers. (Zimmermann, 2010) Why were these animals never mentioned even when questions were asked in Parliament?    
It might well be due to the high mortality rate. 14 animals out of 36 died, however the time frame has not been revealed. 

This population at Karakamia represented the most northern extent of the western ringtail possum’s geographic range (Department of the Environment, 2018).

A study to estimate population size at Karakamia was conducted 15 years after the first releases, when all of the founder individuals would have died. The estimate of 28 individuals (distance sampling) therefore indicates successful breeding and a small but well persisting population. (Zimmermann, 2010) The relatively low number however also indicates a low carrying capacity of the habitat.
Even though introduced predators were fenced out, predation was still fairly high. Carpet pythons and birds of prey seem the major predators but heat stress was reportedly a major contributing factor as almost all deaths occurred during summer. (Zimmermann, 2010)

Management decisions could now be based on these reliable estimates and regular, efficient monitoring would detect population trends. Clarke recommended a monitoring frequency of 1-2 years (Clarke, 2011) and with established line transects from the study, this should not have been onerous, however, 7 years later it was revealed that no ringtail possums could be spotted. Those reportedly extensive surveys at Karakamia seem to have come far too late to detect the population’s downward trend. 

Tone Perup Nature Reserve is located east of Manjimup within the ‘Southern Jarrah Forest area’ of which 17% are protected within conservation reserves. The area is important for native fauna conservation and one of the last natural refuges for many threatened species in southern WA. (Perup management plan, 2012)

The wider area once contained the biggest non-coastal population of ringtails but the animals are now reduced to undetectable levels. (Wayne et al, 2012) 
A 400 ha predator-proof fenced enclosure has been known for protecting an emergency colony of woylies but has now also been used as a translocation site for ringtail possums.
The reason for the devastating decline in the region was assumed to be predation and a fenced enclosure would therefore eliminate this threat. In 2012 30 ringtails (20 adults, 10 offspring) that were displaced due to the development of the Busselton Health Campus were transferred from this almost exclusive peppermint habitat into the secure sanctuary without any peppermints. Only 10 adults were radio-collared and monitored and 3 of those were already dead in the first 3 weeks (plus one offspring). (Hansard 27 Nov 2012)
The cause of death was reportedly raptor predation (anecdotal).
Monitoring results for the hospital area have been readily available, however strangely nothing can be found about the translocated animals.
The last I heard was that in early 2017 3 ringtails have been sighted which would indicate that at least not all died before they could breed.
A lack of transparency and of available information makes it questionable whether this translocation can be deemed a success.

A lack of monitoring and reporting is often cited as the main obstacle for evaluating success or failure of translocation, however even keeping track of numbers seems too hard. When adding up above figures, 694 ringtails were translocated while only 618 animals were officially acknowledged. (see: Morris et al, 2015)

If translocations become necessary due to development pressures in urban areas, they are deemed salvage translocations, not conservation translocations. 
However, development pressures have always been the main reason for translocations of western ringtail possums, which would mean that they should not even have been considered according to the DPaW’s WA Terrestrial Threatened Fauna Translocation Strategy as “the strategy considers translocation for conservation purposes only. “ (Morris et al, 2015)

There is some saving grace in the fact that as far as I know all those ringtail translocations were fairly well monitored and reported while salvage translocations often lack management.
Obviously it all depends on the definition of the term in every individual case.