RE-INTRODUCTION
RE-INTRODUCTION is the restoration of a species into its original habitat, by transferring animals from captive-bred populations or from populations surviving in other areas.
Feasibility Study
Before considering a re-introduction program, the factors which caused the species to go extinct in the wild in the first place must be identified and rectified. Otherwise the re-introduced population will suffer the same fate as the original wild population.
Site selection
When choosing a release site, both ecological and logistic factors must be considered. Ecological requirements such as climate and habitat type must be optimal for the species being released. Its food species and suitable breeding sites must be present. Therefore a detailed ecological survey of the area must be carried out before release. A thorough literature search to determine the ecological requirements of the species must also be carried out. Logistical considerations in site selection include, access, availability of accommodation for staff, and availability of local manpower. The site must also be defendable against encroachment and hunters.
Selecting individual animals for release
Animals might come from zoo populations or from surviving wild populations, provided that removal of animals doesn't threaten the survival of the source population. Sometimes animals are captured from "doomed" populations i.e. those which are certain to go extinct due to imminent habitat destruction. Wild-caught animals must first be kept in quarantine to determine whether they are carrying diseases. For captive-bred animals, the pedigree of animals is usually known and inbreeding can be minimized by selecting only non-related animals for re-introduction.
Pre-Release Procedures
Re-introduction begins by establishing a small breeding population in an enclosed area in their natural habitat, within or close to the release site. This enables the captive bred animals to form natural social groups, become acclimatized to the natural habitat, learn how to find food for themselves and avoid predators. Scientists can observe the animals’ behaviour under near normal conditions to determine how the habitat could be modified to increase the animals chances of survival. Animals showing medical problems can be removed and treated easily. Radio collars are attached to some individuals so that they can be followed after release.
After Release
After release, further research is necessary to determine the food preferences of the animals, their daily movements, their interactions with other species and the reasons for any mortality. Post-release support might include providing extra food or artificial breeding sites, predator control and most importantly PREVENTING HUNTING OF THE RE-INTRODUCED SPECIES.
The Arabian Oryx Re-introduction Project
Hunters exterminated the last herds of the Arabian Oryx in the wild in 1972. Biologists in the US began to establish a captive herd of Oryx in 1963 and by the late 1970’s the captive herd was thriving. Between 1982 and 1984, 21 Oryx were released from the captive herd into a nature reserve in Oman in a large enclosure. Several calves were born in the large enclosure. Before the enclosed herd could be released into the wild it had to meet two criteria: i) the Oryx had to have developed a stable social hierarchy and ii) they had to exhibit the full range of social and sexual behaviours. Both these criteria were met after 24 months in the enclosure. The herd was monitored after release and the cause of each death determined. The project has been very successful. The herds of Oryx are now protected by the local people.
Orang Utans
Efforts to re-introduce captive-reared Orang Utans into the wild have been much less successful. In Indonesia it was made illegal to own Orang Utans as pets. Many were confiscated from private owners and sent to re-habilitation centres in the forest for readjustment to the natural habitat and eventual release into the wild. Initially animals were kept in quarantine to check for diseases. Then they were trained to climb trees (a skill they lost when kept in cages) and to forage for food. Next the orangs were released into the forest near the forest station, but they received extra food by visiting a feeding station every day. Unfortunately most released orangs never became fully independent of the feeding stations.
The problems with re-introducing primates are far more complex than those of re-introducing ungulates. Primates lead complex social lives. They feed on a very wide range of food and live in a very complex habitat. The infant must spend a long time with its mother to learn all the skills needed for survival. Captive-reared animals lack these skills and cannot be taught them adequately by humans. Orang Utans breed very slowly so the re-introduced populations increased very slowly