Relocation – translocation – (re-)introduction
The termini translocation and relocation are both used for the same action and can therefore be seen as interchangeable. According to the IUCN guidelines (IUCN, 2013) it means the ‘human-mediated movement of living organisms from one area, with release in another’.
https://www.iucn.org/content/new-guidelines-conservation-translocations-published-iucn
Translocations can lead to reintroductions, reinforcement/re-stocking and conservation introductions/assisted colonisations. While reintroduction and reinforcement happen within a species’ indigenous range, introductions/assisted colonisations translocate organisms outside their indigenous range. (IUCN, 2013)
Reintroductions move species to an area of former geographic distribution from which they have disappeared with the aim of establishing new populations. If reinforcement of those conspecifics already present becomes necessary to boost numbers, to increase genetic diversity or to avoid numbers to go below the threshold of viability, re-stocking is conducted. The ultimate aim would be recovery to self-sustainability, however in reality it usually only prevents population extinction. (Jakob-Hoff et al, 2015)
If previous translocations are yet to demonstrate success, translocations are deemed experimental.
Assisted colonisation of species outside their historic ranges is a fairly new conservation tool. It could become necessary in response to for instance climate change. However, it is the most risky kind of translocation and potential ecological damage such as harm to native species in the release area and assessment of invasion risk need careful consideration. (Seddon et al, 2015)
The 5 major risks to host ecosystems are according to the IUCN (IUCN, 2013): ecological risk, disease risk, associated invasive risk, gene escape risk and social-economic risk.
Nevertheless, the practice has been employed with more successes than failures in Western Australia and South Australia, however mostly to predator free islands, which most likely contributed significantly to the good success rate. (Seddon et al, 2015)
The translocation of native species is primarily associated with planned programs to assist the conservation of a species, provides an emergency rescue of members of a species in the face of an unforeseen risk, or the salvage translocation of individuals that are likely to be affected by land-use change. (Nally and Adams, 2015)
Translocations of western ringtail possums from their last major stronghold – the core area around Busselton/Dunsborough - were usually undertaken as a management strategy to mitigate the effects of habitat loss through land clearing for development, if these developments were regarded as unavoidable due to social and economic reasons and impacts on the species were expected to be significant. (Clarke, 2011)
Shifting of animals that deserves the name ‘conservation translocation’ needs to provide clear conservation benefits at population level, species- or ecosystem level and not just to the translocated individuals.
Translocation of animals displaced by development would therefore fit the criteria for ‘salvage translocation’ and it is doubtful whether they can truly be effective for mitigating the impact of habitat loss. They might even increase the risk of ‘death by a thousand cuts’ as they make it seem ‘normal’ to just shift animals to facilitate ‘business as usual’.
If the suitability of a release area is not proven for a species or their successful establishment is in question, salvage translocations are not deemed conservation translocations according to the IUCN and should not be allowed (Seddon et al, 2015, IUCN, 2013). However Annex 2 of the guidelines then includes the term ‘mitigation translocation’ for the same actions and that way associate some benefits with this type of translocation. (Moro et al, 2015)
Salvage translocations are frequently promoted as conservation translocations and it seems that they are at times actively marketed by some environmental consultants who are engaged to undertake flora and fauna surveys and prepare impact assessments and propose mitigation options.
However, the IUCN guidelines emphasise that ‘rigorous analysis and great caution should be applied when assessing potential future conservation benefits and using them to mitigate or offset current development impacts, in view of the inherent uncertainty regarding translocation success.’ (IUCN, 2013)
Translocation itself as an activity has not been specifically considered in legislation in Australia.
The intergovernmental Australian and New Zealand Environment and Conservation Council (ANZECC 1991-2001) produced the draft policy for translocations of vertebrate animals in Australia. It was formulated as a national policy as recovery actions for many species crossed state boundaries. The ANZECC guidelines included the notions of being consistent with a species Recovery Plan, the use of Animal Ethics Committees, and the need to develop a Translocation Proposal for each instance. (Nally and Adams, 2015)
To deal with both the increasing use of salvage translocation and the need for national consistency, the Australian Government published a policy statement on how translocations would be considered under the EPBC Act in 2009 and revised it in 2013 (Sustainability, Populations and Communities 2013). The EPBC Act requires decisions to take account of the ‘precautionary principle’ and policies emphasise the need to treat predictions of ‘success’ with some caution due to the poor conservation outcomes associated with salvage activities. (Nally and Adams, 2015)
We can only try to remain mindful that translocation is a human construct that serves an often overlapping set of objectives.
In theory removing animals from their habitat is a last resort as the conservation outcome is highly uncertain. It might not even reduce the level of impact on the affected wildlife. In general, translocation should only be considered if it can be demonstrated that no irreparable harm will be done to the species. However, in reality developments were always approved regardless and translocations conduced.
By the late 1980s, it had become widely acknowledged that most reintroduction/translocation projects were poorly conceived, badly monitored and regarding threatened species usually unsuccessful. (Griffith et al, 1989)
The most comprehensive reviews of translocations within Australia were conducted by Short in 2009 and by Fischer and Lindenmayer in 2000.
The outcomes of 40% (152) of 380 documented translocations of 102 vertebrate species remained unpublished. Only 54% of those reported were deemed successful. (Short, 2009)
If unsuccessful the outcomes are less likely to be published which might lead to a repetition of the mistakes in the next program. (Fischer and Lindenmayer, 2000)
Publishing the design, procedures and results regardless of the outcome would clearly increase the learning curve. However, even the published information is mostly inadequate. (Moro et al, 2015)
Translocation programs need to be designed with realistic objectives, well planned, appropriately implemented and sufficiently resourced as a failure carries not only a high risk for the translocated animals but also for the new environment and the already present population.
In Australia, predation by introduced feral cats and red foxes has been the primary cause of failure in the majority of translocations, particularly when predator-naïve marsupials were the target species. (Short, 2009)
As predation is only one of many habitat features, it is questionable whether predation was truly the reason for the animals’ demise or only the final result of a longer process.
Other extrinsic factors such as the unsuitability of the recipient environment - for ringtail possums in particular low nutritional food quality - might be the underlying causes for vulnerability to predation.
Intrinsic factors such as the size, characteristics and health of the founder group and the stress responses of the reintroduced animals to translocation could also induce population-level effects through high mortality, disrupted reproduction and dispersal issues. (Dickens et al, 2010, Batson et al, 2015)
Judy Clarke’s study (Clarke, 2011) investigated some of the possible factors limiting translocation success; however the confounding complexity of interacting factors would be outside the scope of any single investigation.
Ideally translocations should be replicated and controlled, but this is often not possible as appropriate habitat areas are very limited, there are rarely enough individuals available for replication and financial restraints are crippling. (Kemp et al, 2015)
All relocations are unique as they also present site-specific challenges. Challenges could change with changing environmental conditions such as drought and resulting habitat deterioration or an unexpected influx of competitors or predators.
Effective and reliable monitoring would be the cornerstone of any determination whether the program was successful, for decisions regarding the management of the population and to work out strategies for future programs. However, long-term monitoring is rare.
