THIS ISSUE
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THE ZOOLOGIST ISSUE 15 | SPRING 2024 | EXCLUSIVELY FOR ZSL FELLOWS
Chad's Ouadi Rimé-Ouadi Achim Faunal Reserve is now home to an estimated 600 wild scimitar-horned oryx, growing from a population of around 250 reintroduced oryx
DESERT ANTELOPE FINDS ITS OASIS
IUCN downgrades scimitar-horned oryx to Endangered, following reintroduction programme
T
he end of 2023 marked a new beginning for one species of desert antelope. In December, the scimitar-horned oryx (Oryx dammah) was officially recognised as having returned to the wild, downgrading the species from Extinct in the Wild to Endangered on the IUCN Red List. It was a return two decades in the making, explains Tim Wacher. The reintroduction of scimitar-horned oryx to Chad’s Ouadi Rimé-Ouadi Achim Faunal Reserve began in 2016 – 16 years after their official extinction in the wild. The 77,950km2 area on the edge of the Sahara Desert had formed the heartland of the oryx’s range 60 years ago. The programme started with an initial release of 21 oryx; today, over 250 oryx have been released into the Reserve and the wild population is estimated to exceed 600 individuals. ZSL is one of several implementing partners, part of a project led by the Government of Chad and the Environment Agency of Abu Dhabi (EAD), with Sahara Conservation. “Our role has been to train the Chadian ranger team and support an intensive post-release monitoring programme,” says Tim Wacher, ZSL’s Senior Conservation Biologist on the project. The monitoring programme, and the incredible success it has illustrated, was crucial to the oryx’s reassessment by the IUCN. “We were able to show that the released oryx have around 85% annual survival rate, and wild-born calves are equalling or even exceeding it.” Birth rates have also been high, with females giving birth every nine months, on average. Over 500 wild calves have been born and there are already a handful of mothers in the Reserve who have had nine calves in just seven years.
Tim puts the success of the project down to the ambition and clear direction of its partners and funding. “The EAD have ensured the project operates to the highest standards, from creating state-of-the-art facilities to reintroduction logistics and post-release follow up. The attention paid to recommendations from the international stud books to assemble fully representative genetic lines and high-quality veterinary care, including preparation with appropriate vaccines, are all indicators of the significant commitment behind the project.” In 2014, ahead of the planned reintroduction, the breeding facility in Abu Dhabi was established with oryx from zoos around the world, including two females flown from Whipsnade Zoo. The descendants of that herd of oryx assembled in Abu Dhabi, known as the ‘world herd’, now roam the grasslands in central Chad. “The oryx are proof that, if you allocate resources and follow the science, success is possible.”
Challenges on the horizon However, further commitment is needed to ensure the oryx's continued success in Chad, says Tim. “They have shown that they can flourish under current conditions, but keeping it that way will be a challenge.” The drilling of freshwater wells to meet the needs of the growing human population and livestock is a key issue in Chad, where water sources are limited. Presence of wells has been shown to impact desert antelope behaviour, and unregulated drilling of new wells in the Reserve poses one significant challenge for the future of the oryx.
“The oryx comfortably share the Reserve with traditional herders and their livestock, who live in step with the seasons and have minimal impact on the land. However, development of large-scale commercial livestock management, coupled with unplanned increase in artificial water points, can easily stress the naturally arid environment.”
Restoring the Sahelian ecosystem
Long term, the project doesn’t stop at the oryx – the ambition is to restore the wider ecosystem by reintroducing other locally extinct species. Since reintroductions of the oryx began, the project has expanded to reintroduce addax (Addax nasomaculatus) and North African ostrich (Struthio camelus camelus). Work is also underway to protect and reinforce the remaining population of 50-60 dama gazelles (Nanger dama) in the Ouadi Rimé-Ouadi Achim Faunal Reserve, representing perhaps 25-30% of the remaining wild population. “It’s a spectacular sight, large herds of oryx back in their natural habitat, living free in their original landscape and entirely independently once more,” says Tim. “The basis is there for oryx and other desert species to flourish again in Chad. Their future is down to the management of both the landscape and Tim Wacher, Senior Conservation Biologist, ZSL the inevitable pressures they will face.”