The release of individuals at a chosen location is the defining feature of reintroduction programs. However, the choice of an adequate release protocol for translocated individuals can be complicated, particularly for programs with multiple objectives, such as maximising release numbers while minimising impacts on the source population. Limited resources and the biology of species can also generate trade-offs, such as where older individuals have greater survival but are more expensive to translocate or breed. Uncertainty will surround many of these aspects: yet decisions must be made, often within strict time frames. This chapter illustrates how a structured decision-making framework can be used to guide the choice of release strategies in complex reintroduction programs. This approach focuses on clearly specifying objectives, comparing the available actions by their expected outcomes and explicitly considering uncertainties and trade-offs. An example is provided using the release program for the endangered southern corroboree frog Pseudophryne corroboree. For a 10-year release program for this species, mixed releases of eggs and sub-adults are expected to maximise the persistence of both wild and captive populations, while meeting budget constraints. Decision-analytic methods can help managers design transparent and effective release strategies, making rational decisions in the face of uncertainty.

Parasite and other health hazards can pose substantial risks to reintroductions. It is therefore important that managers identify these hazards, estimate the risks they pose and, where deemed necessary, develop ways to manage these risks. A variety of approaches to disease risk assessment have been adopted in the Australasian region. Here we provide a brief review of the most common approaches to managing parasite and other health hazards in reintroduction. We discuss the respective strengths and weaknesses of each method and suggest ways we can improve our disease risk management into the future. In particular, we emphasise that risk assessment should be integrated in the broader decision process of a reintroduction program, maintaining a clear view of the overall management objectives, and then carefully creating and evaluating alternative management actions, including monitoring and surveillance.

The aim of any trial or experimental reintroduction is to consider key questions relevant to improving the likelihood of population establishment and persistence. These questions relate to the ecology of the focal species and the suitability of the release environment. Although trial reintroductions provide insight, and generate hypotheses relating to an organism’s persistence and establishment, experiments (controlled manipulations with replicates) allow clearer conclusions. However, given that reintroductions often involve threatened species, experiments may be impossible due to small sample sizes and few opportunities for replication. As such, trial reintroductions are often the only option available to get an indication of which factors influence establishment success, habitat use and requirements, tolerance of threats, competition for resources, and social and spatial requirements. Thus trials remain a valuable tool for conservation managers, provided they are interpreted cautiously, with clear understanding of the parameters documented for each trial. Trials can also be combined strategically within an adaptive management framework. Here we outline the roles of trials and experiments, provide some case studies, and offer some advice for handling the limitations inherent in both reintroduction experiments and trials.

Assisted colonisation – the translocation of organisms with release in areas outside their indigenous range in response to threats such as climate change – was presented in the scientific literature only a few years ago as a new tool for species conservation. The idea of planned introductions for conservation is a controversial issue, prompting vigorous, and sometimes ill-informed, debate in the scientific literature. The broad consensus was that this represented a bold new direction that had merit but carried great risk. Unacknowledged by most commentators, assisted colonisation (by other names) was already taking place, and in Australia and New Zealand was even a long-accepted part of the conservation management tool kit. In 2013, the IUCN recognised assisted colonisation as a legitimate, if inherently risky, conservation translocation, and set out a comprehensive set of guidelines for its application. We review the history of assisted colonisation, with a focus on Australian and New Zealand projects moving species in response to threats within the indigenous range. We review the current status of assisted colonisation in Australia and New Zealand and present two case studies to illustrate the application of new approaches for assisted colonisation planning: Australia’s western swamp tortoise (Pseudemydura umbrina), and New Zealand’s hihi (Notiomystis cincta). We conclude by considering future directions in the specific application of translocations for climate change mitigation in the region.

The Tasmanian devil is threatened by a transmissible cancer, devil facial tumour disease (DFTD), which has induced a decline of greater than 80% in the wild population. An insurance population has been established with the goals of maintaining an effective population of > 500 devils for 50 years that is DFTD-free, is genetically representative, is able to sustain a harvest for wild release, maintains a suite of associated flora and fauna (commensal, symbiotic and parasitic), and maintains wild behaviours. The insurance metapopulation now includes more than 550 individuals, from 128 founders, secured at 28 institutions in a combination of intensive captive-breeding enclosures, managed environmental enclosures, free-ranging enclosures, and a population introduced to an island outside the species’ known historic range (i.e. a conservation introduction). In the next few years, the insurance metapopulation will incorporate wild-living, DFTD-free Tasmanian devil populations secured within their current range. Translocation of individuals occurs between multiple facilities, locations, Australian states and nations, and is influenced by a disease risk categorisation. The metapopulation is managed by generating recommendations for founder animals, breeding, translocation and harvesting, based on pedigree and genetic data using SPARKS and PMx software, supported by population modelling using VORTEX software. To achieve an effective population size (N_e) of 500, the minimum metapopulation size will need to build to between 1500 and 5000 individuals in order to maintain gene diversity at ≥ 95% for 50 years, while also replacing lost diversity. However, through biosecurity, risk categorisation and quarantine procedures, it is feasible to harvest from, and incorporate, diseased wild populations should they persist, permitting a lower metapopulation size.

The reintroduction of locally extinct species into their former range has become an increasingly popular conservation goal. Some of these species have the capacity to modify or maintain abiotic environments, via a range of activities, such as digging for food. These species, termed ecosystem engineers, can have a disproportionate influence on ecosystems by creating different habitat patches, with flow-on effects on other biota. In Australia, there has been increasing recognition over the past decade of the role of small soil-foraging mammals for maintaining and or reinstating important ecosystem functions and processes. Although the science underpinning the reintroduction of these ecosystem engineers is well established, policy aimed at facilitating ecosystem engineering is in its infancy. The move towards reintroducing these animals has largely been initiated by NGOs, with support from government. Here we discuss the policy implications of using small mammals to achieve land management co-benefits and highlight the opportunities that these ecosystem engineers represent for achieving cost-effective and appropriate conservation outcomes. We use the case study of the ‘Saving our Species’ program of the New South Wales Government to illustrate a potential future pathway for conservation policy that harnesses ecosystem engineers.

Over the past 20 years, zoos have enhanced their contributions to reintroduction programs through active pursuit of collaborative partnerships with governments, academic institutions and NGOs, and the application of good science. A ‘One Plan’ approach that integrates conservation planning of in situ and ex situ populations is becoming standard practice. In support of this, zoos are broadening the range of training staff receive in field conservation skills and enabling them to apply relevant ex situ animal management techniques in direct support of field conservation. Zoos in Australia and New Zealand are therefore becoming true multi-disciplinary conservation organisations that are well positioned to make meaningful contributions to the continuing development and application of the science and art of reintroduction biology.

Fish translocations are fundamentally different to those of other vertebrate groups, with orders of magnitude more individuals usually released, and these individuals usually having high subsequent mortality. Translocation programs for Australian freshwater fish have changed considerably in the last 30+ years, moving from wild-to-wild translocations to hatchery stockings for recreational fisheries. Hatchery stocking and wild-to-wild translocations are now also used for conservation purposes. Translocations are among the four most-common management interventions employed for threatened Australian freshwater fish, with the frequency of wild-to-wild translocations, stockings and rescues increasing significantly during the recent Millennium Drought (1997–2010). We document 99 translocations of Australian freshwater fish conducted for conservation purposes since the late 1980s. These were all reintroductions (releases to sites formerly occupied by the species) or reinforcements of existing populations, except for one conservation introduction. Excluding cases where it is too early to assess the outcome, or where remnant populations were present when the reintroduction occurred, 38% of the translocations claim full or partial success. However, for 16% the outcome is unknown, raising concerns about the adequacy of monitoring. Monitoring programs associated with fish translocations are often short-term, under-resourced and, for long-lived fishes, monitoring often only encompasses the first milestone of success (survival for some period after release), with subsequent milestones (breeding and establishment) left unmeasured. Case studies review new insights into fish translocation such as: optimal stocking strategies; the survivorship and dispersal of on-grown individuals (i.e. hatchery-reared beyond the juvenile stage); the use of captive maintenance and subsequent release; and the use of artificial habitats (‘natural hatcheries’) to increase production numbers. Future freshwater fish translocations require increased levels of investment and will likely benefit from combined approaches of stocking and wild-to-wild translocation, along with consideration of further conservation introductions.

Worldwide, humans have intentionally translocated plants and animals wherever they have ventured, primarily for nourishment, cultural or economic objectives. Over the past 200 years, the majority of Australian and New Zealand translocations have been mainly introductions undertaken by governments for the development of agriculture. Approval processes have reflected the cultural norms of the era, but until recently were focused on relatively unfettered encouragement. Although probably commencing in the late 1800s, conservation translocation activities substantially increased in the 1960s in New Zealand and the 1990s in Australia, leading to the development of policies and protocols that form the basis for approval requirements. Informed by a body of practice, and the International Union for the Conservation of Nature’s (IUCN) guidelines, policies focused on improving the practice of translocation proliferated in the 1990s. Although they continue to be refined for conservation translocations, the increasing use of advocacy-driven and salvage translocations (which include ‘mitigation translocations’ as defined by the IUCN) provide new policy challenges. A smaller, more integrated set of policy layers may balance the users’ needs and allow sufficient project specificity while encompassing the breadth of circumstances under which translocation is being used.