RT06: Bird re-introductions, pre-release preparations, releases and post-release monitoring: Improving the rigour of re-introduction project assessment, planning and execution

Seddon, J.P & Cade, T.J. 1999. Bird re-introductions, pre-release preparations, releases and post-release monitoring: Improving the rigour of re-introduction project assessment, planning and execution. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban: 3174-3176. Johannesburg: BirdLife South Africa.

The re-introduction of captive-bred birds, or the translocation of wild birds, into adequate areas of suitable habitat within their former range is becoming increasingly popular as a means of restoring populations of endangered species. The transition from captivity to the wild, or from one locality to another is seldom easy. Captive-bred birds must learn the necessary skills to find food and shelter and avoid predators, while even wild birds must establish territories within the release site. If newly established populations are to become self-sustaining, released birds must find mates and nest sites, lay eggs and raise chicks. Managers of re-introduction projects must attempt to prepare birds for release, release them in such a way as to enhance the likelihood of survival, and monitor closely the fate of the released population.

In the past many wildlife reintroduction projects have been characterised by poor planning, a lack of theoretical background, and a lack of involvement by professional biologists. Projects have operated in isolation, with little input from other efforts, and have either not published results, or have published only in grey literature. To a large extent the creation of the Re-introduction Specialist Group (RSG) of the IUCN’s Species Survival Commission network has begun to address these shortcomings and to provide international co-ordination and focus. With the aim of standardising procedures for re-introductions the RSG has produced a set of Re-introduction Guidelines. However, because these are intended to be broad policy guidelines they have limited use in the planning of specific projects. One way to address this gap is to compile a database of case studies, and to use these within formal re-introduction planning workshops, much in the same way as the IUCN’s Conservation Breeding Specialist Group conducts and facilitates Population and Habitat Viability Analysis workshops.

The focus of the round table was therefore to start working towards a set of taxon specific guidelines for use in the planning and revision of re-introduction projects by identifying some of the important principles that relate to the success of bird re-introductions. Some of these ideas that arose from the discussions are set out in brief below.

Re-introduction projects may provide the best opportunity for undertaking ecological and behavioural studies in a relatively controlled environment, and may provide populations in which the identity, age and sex of each individual is known. There is also the opportunity for testing hypotheses, especially in population biology and thereby improve the theoretical basis for conservation management actions. Key considerations include the following: (1) It should be remembered that re-introduction is one tool available for species restoration and if the re-introduction process is selected, planning and execution must be undertaken with scientific rigour. (2) Project design should keep the main aim in mind, the establishment of secure populations, and to this end must seek to understand the demographic parameters of the released population. (3) Project design should also be based on a good understanding of the basic biology of the target species; understanding can be improved by work on a similar species. (4) Experimental re-introductions should be designed as experiments. (5) Opportunities should be taken for conducting ecological studies in conjunction with re-introductions. (6) Re-introductions are long-term, costly exercises and require full and prior commitment of funding, manpower and other resources.

It has been shown that post-release predation can be significantly reduced by appropriate predator training.

Birds may often need to adapt to the food items present in the release site. This can be facilitated by rearing and releasing on site, or by training to digest certain material. Disease exposure may be a problem for released birds. This could be overcome through vaccination, or other exposure to infectious agents before release.

The social groupings of released birds may be important. Such groups may be maintained throughout the entire rearing period. The presence of wild or experienced conspecifics may facilitate learning about the new environment, although where these are absent specific pre-release training is possible.

The way in which a bird is released can be critical to early survival and establishment, particularly if a transition from captivity to free-ranging must be made. This area of re-introduction planning has perhaps received the most attention to date. Three general areas of interest were identified.

Selection and preparation: The life history traits of a species will give a clue to the evolutionarily most suitable habitat, reinforcing the need to understand the biology of the target species when planning a re-introduction. It is necessary to avoid making the assumption that species in the wild are in optimal habitat, as the present day distribution may be the result of range reduction due to habitat loss and disturbance. Behavioural plasticity may mean that a species will do well in modified habitats, while some species may do better in sub-optimal habitat, possibly because such areas hold lower densities of predators.

Assessment and removal of causes of decline: While these causes should be assessed and mitigated whenever possible, it is important to consider that new threats may exist. Threats may come from other native species and a decision needs to be made about conservation priorities.

Artificial range extensions: In keeping with the idea that habitat outside the known range may be suitable, releases could take place into new areas. Accidental introductions may also provide clues as to those habitat features that may be important for a species.

It has been shown that wild-to-wild translocations have greater success than the release of captive-reared birds. As long as wild stock is available, and the collection of wild birds does not deplete existing populations, translocations may be an effective means to establish new populations. Effective techniques for the capture and translocation of wild birds will vary greatly between species, knowledge of target species biology is essential. Considerations include: (1) capture and handling techniques, (2) social and other groupings, and (3) measuring impacts.

It is crucial that release programmes be conducted in such a way that interpretation of results is possible. Survival after release may vary due to a number of factors, including annual variation in climate, food supply or predator numbers, as well as the release techniques used. By making rigorous comparisons between different techniques and different conditions is may be possible to select the most appropriate method to maximise immediate post-release survival. Some considerations include: (1) hard versus soft release techniques; (2) controlling predators, and (3) supplementary provisioning.

Monitoring of birds after release is one of the areas that has been most neglected. Although labour-intensive, it is the one means of measuring the progress of a re-introduction project, and is essential if any assessment of outcome is to be made. At the least, all released birds must be individually marked. Because of the difficulty in observing and identifying individual free-ranging birds, radio-telemetry is often necessary. Although expensive, the use of conventional radio- or satellite tags, will greatly improve the quality of information that can be obtained. Assessment of success may appear to be a fundamental consideration, the goal of re-introductions is to establish a self-sustaining population that will eventually need little management input, but how do you know when to stop releases? To derive suitable criteria to measure success we need to improve our knowledge of the released population’s demography. Key points include: (1) telemetry, techniques and technology; (2) impacts on extant flora and fauna, assessment and mitigation; (3) assessment of success - how do we know when to stop? (4) viability analysis modelling, what do we need to know about released birds?

One approach is to compare the performance of the released population with natural population dynamics. The aim would be to achieve a low probability of extinction. To assess this through modelling requires accurate estimates of survival, obtainable only through intensive monitoring. If a wild population is not available for comparison, it may be possible to make intergenerational comparisons, since there is an expectation of improved productivity in wild-born generations. It cannot be stressed too much that the ultimate assessment of success or failure of any bird re-introduction is dependent on long-term monitoring.

These could be held in conjunction with larger gatherings, e.g. behavioural ecology and conservation biology meetings, and taxon specific meetings. The RSG could also promote regular meetings of the section chairs to improve across taxa development of re-introduction principles. The development of Re-introduction Assessment Workshops would represent another opportunity for effective networking. Informal contacts will be facilitated following publication of the Re-introduction Practitioners Directory, a listing of all re-introduction projects registered at the RSG, with contact names and addresses.

Such a site could post general information about the IUCN, the SSC and the RSG. It should advise on project success and failures, and post reports and other grey literature. It could also contain the Re-introduction Guidelines, and the forth-coming Re-introduction Practitioners Directory and its revisions, and should have links to related sites, e.g. other SSC specialist groups, Recent Ornithological Literature and other databases. A comprehensive and active database of re-introduction publications could be maintained.