Newswise — Scientific evidence has now demonstrated that the progressive reintroduction of primates into their natural habitat, accompanied by support following release, has, for the very first time, exhibited enhancements in their overall welfare.
Annually, wildlife rescue facilities liberate animals considered prepared for release into their native environment, assuming that these creatures will flourish best in their natural habitats. However, this assumption, specifically concerning primates, has yet to undergo scientific scrutiny.
Researchers from Durham University, Disney's Animals, Science and Environment, and the Jane Goodall Institute have successfully demonstrated the successful adaptation of a carefully reintroduced group of mandrills to their natural habitat.
Following their reintroduction to the wild, the animals exhibited a lower stress response in their natural habitat compared to their time spent at the sanctuary.
The research is published in the academic journal Conservation Physiology.
Maintaining a low stress response in animals during the release process is crucial, as high levels of stress can hinder their ability to adapt and thrive in the new environment. If an animal experiences excessive stress, it may lead to unsuccessful release attempts, requiring the animal to be returned to human care. In some cases, such stress-induced failures can result in the animal's unfortunate demise.
The study indicates that a meticulously designed release strategy, involving a pre-release enclosure and diverse forms of post-release support, can be highly effective for the successful integration of wild-born, orphaned mandrills who have undergone rehabilitation in a sanctuary.
The International Union for Conservation of Nature (IUCN) has established guidelines for primate re-introduction, emphasizing the importance of a gradual release process and subsequent monitoring. However, due to limitations in terms of cost and time, these recommended practices are often not fully implemented.
According to the authors, their study offers compelling evidence supporting the notion that a deliberately gradual and methodical approach is pivotal for the success of re-introductions, as well as for the overall well-being of the animals involved.
The release process encompassed several essential elements for the mandrills, including a period of acclimation within a pre-release enclosure situated in the forest, supplementary food provisions, regular observations of the animals' well-being, and necessary interventions to address any individuals experiencing difficulties during the transition.
Professor Jo Setchell, who spearheaded the research and is affiliated with the Department of Anthropology at Durham University, emphasized the scarcity of studies that have actually examined the impact of primate releases on animal welfare. While numerous primate releases operate under the assumption that they enhance welfare, the empirical evidence supporting this claim is limited.
"Our efforts employ rigorous science in validating this presumption, presenting proof that a meticulously orchestrated release of mandrills can yield favorable outcomes with appropriate configuration, surveillance, and assessment."
The observed mandrills, rescued in this investigation, had suffered orphanhood due to hunting and were saved by the Congolese authorities. The hunting of mandrills for sustenance poses as a significant peril to their conservation.
Similar to numerous primate relocations, the core impetus behind this initiative was to enhance primate well-being. Presently, wild mandrills do not require population augmentation. Nonetheless, considering the decline in approximately 70 percent of primate species' populations, accomplishing prosperous reintroductions will progressively assume greater significance in the times ahead.
Operating within the Republic of Congo, the group relocated 15 mandrills from the Tchimpounga Sanctuary to an initial holding area within Conkouati-Douli National Park, followed by their subsequent release into the park. Throughout the transfer process, the team acquired fecal samples from the mandrills, enabling them to assess their stress response. By employing fecal samples, the team could measure the mandrills' stress levels in a non-invasive manner.
Following the relocation of the animals from the sanctuary to the pre-release enclosure, their stress response exhibited an initial upsurge. This outcome confirmed the researchers' expectations that the transportation process, involving crate transportation by both car and boat, would induce stress in the mandrills.
To the astonishment of the researchers, the stress response of the mandrills did not exhibit any noticeable increase upon their release into the forest. This unexpected outcome suggests that the mandrills were able to adapt smoothly to their natural habitat without experiencing significant stress.
Merely a month after being released into the wilderness, the mandrills' stress response plummeted below the levels observed during their time in the sanctuary. Remarkably, after a year of living in the wild, their stress response was approximately half of what it had been in the sanctuary, indicating that the mandrills were thriving in their natural habitat.
Dr. Miles Woodruff, affiliated with the Jane Goodall Institute, served as the Principal Investigator of the Mandrill Reintroduction Project. He undertook this study as part of his completed PhD program at Durham University.
Dr. Miles Woodruff emphasized that the project's ultimate success was the result of meticulous pre-release preparations and comprehensive post-release support. The extensive efforts put into conducting this study were driven by the significance of learning from all releases and reporting the outcomes for future reference.
Dr. Miles Woodruff expressed the criticality of dealing with the survival of crucial species in delicate environments, where the value of each individual is paramount. The findings of the study were deemed highly exciting as they provide physiological evidence that substantiates the rationale behind the International Union for Conservation of Nature's (IUCN) recommendations to carry out soft releases of animals.
Out of the 15 mandrills that were released, all of them managed to survive, and the exciting news was that two infants were born during their time in the wild. However, it is worth noting that three individuals from the original group were eventually returned to the sanctuary as their transfer and adjustment to the new environment did not go as planned.
The research was funded by the Jane Goodall Institute and private donors.
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