The majestic Arabian Oryx (image from Arab America)
We often cover some fairly depressing topics on the podcast, but the Arabian Oryx is one of the most significant conservation success stories of modern times!
One of only four oryx species to occur outside of Africa, the Arabian Oryx is a medium sized ungulate with a white coat, a distinct shoulder bump, long straight horns, and a tufted tail. Famous Greek historians Aristotle and Pliny the elder believed that many unicorn myths derived from the Arabian Oryx, and this is easy to understand when the Oryx is seen in profile and their two magnificent horns appear as one. They also have hollow bones in their bones that cannot regrow if they lose or damage a horn, which may have fuelled even more unicorn myths. So iconic and magnificent is the Arabian Oryx that they are now the national animal of Jordan, Oman, the United Arab Emirates, Bahrain and Qatar.
In 1972 they were declared extinct in the wild after their populations were decimated by hunting, but the determination of a team of a scientists and conservationists at the fledgling charity Fauna and Flora International brought them back from the brink, in what is considered the first successful reintroduction of a species to their natural range. Today, they inhabit the stony, sandy steppes of the Arabian Peninsula, and are well adapted to these harsh, arid conditions.
Its’ getting hot in here: the desert adaptions of the Arabian Oryx
Deserts are some of the toughest places any species could find themselves, with little resources and water, cold nights and boiling hot days. But the Arabian Oryx has evolved some incredible adaptations to thrive in these conditions. Behaviourally, Oryx have evolved to be active at dawn in dusk in the cooler temperatures, and rest during the heat of the day, making them a crepuscular species. When they do take their siestas, they dig depressions in the ground with their front hooves, making a sand bed they can shade themselves in. They are frequently nomadic, travelling huge distances to chase the rains that they can seemingly sense from enormous distances away. When the punishing summer months arrive, Oryx drastically reduce their metabolic rate by lying down in the shade and only foraging for food over shorter distances in the cool of night.
But it isn’t just their behaviour they have adapted to survive the aridity of their desert homes, but their physiology too. During the day, oryx allow their core body temperature to rise. This seems insane during the hottest part of the day, but paradoxically this is the key to their survival in the heat. Increasing their blood temperature during the hottest temperatures means that they use less evaporative cooling and retain more of their body water. At night they lower their body temperature back within their normal range, in a technique called heterothermy. They have some of the largest blood temperature fluctuations during the day for any large mammal, with changes of as much as 7.7oC recorded. The structure of their blood vessel network helps facilitate these changes, with a small arterial network with a very large surface area called the rete mirabile. Heat exchange between warm arterial blood and cooler venous blood in the sinus cavities is easily conducted across this specially evolved network. Research has found that its actually the availability of water that drives these temperature changes, rather than the temperature of their environment. When conditions are especially harsh, they can reduce their urine volume, faecal water loss and resting metabolic rate by up to 50%!
An example of the complex network of blood vessels that make up the rete mirabile (image from MDPI)
A unicorn not consigned to myth: the plight and rescue of the Arabian Oryx
The oryx was once one of the most widely distributed species in the Arabian peninsula, even though it was always highly desired for its meat and hide by the nomadic Bedouin tribes. But hunting was always constrained until the introduction of automatic vehicles and weapons made it so much easier to hunt vast numbers. In particular, Arabian Oryx hunting was a favourite pastime of Arabian princes and oil company clerks who had come to make their fortune in the Middle East. These hunts and their catastrophic effects on the Oryx populations were only noticed in 1962, when the species was already plummeting towards extinction. By 1972, the species was declared extinct in the wild.
But fortunately, The Fauna Preservation Society (today known as Fauna and Flora International) realised the imminent collapse of the Oryx species and stepped in to help. Operation Oryx travelled to South Yemen to capture some of the last surviving wild animals to bring into a captive breeding programme at Phoenix Zoo in Arizona. This zoo was selected for the climate, as Arizona has a similar arid environment to the Arabian Peninsula, giving the animals the best chance to thrive. Three of the four captured animals survived the arduous trip to America, where they were supplemented by a female from London Zoo and animals donated from a private collection belonging to the Sultan of Kuwait and King Saud.
A lucky Arabian Oryx born as part of the World Herd at Phoenix Zoo (image from Phoenix Zoo)
After 10 years, the handful of Oryx they had rose to 35 individuals, and 6 were moved to San Diego to continue the breeding programme there. Meanwhile in the wild, the species remained extinct; no surprise, hitherto un-surveyed populations reared their magnificent horned heads. By 1992, there were 1600 Arabian Oryx across zoos and private collections.
Unusually for many critically endangered species, the habitat for the Arabian Oryx was safe, but there were concerns the hunting pressure would still exist. From 1978 onwards, tentative releases were organised, with small numbers of animals released into various heavily protected reserves. By 1996, 300 Arabian Oryx were wild, but the intense hunting started up again, and the animals sadly had to be brought back into captivity. More campaigning and restrictions were brought in to reduce the demand for hunting, and gradually the Arabian Oryx was released back into the wild safely, and populations began to establish themselves.
As of 2011, the Arabian Oryx was relisted as vulnerable by the IUCN red list. Hunting pressures have not been entirely eradicated, and many of the animals caught are captured for private collections.
Although the Arabian Oryx is not completely out of the woods yet, their story still remains one of the biggest conservation successes in history. Populations are closely monitored and, in many places, guarded in reserves and parks. Given they were subject to such an intensive pressure and bred in captivity, in recent years geneticists have investigated the genetic history of the species. Studies from the UAE and Qatar showed that the Arabian Oryx in the region has relatively low levels of genetic diversity, and interestingly showed signs of both inbreeding and outbreeding depression in the wild, although the captive population in Saudi Arabia have quite high levels of genetic diversity. None of the breeding programmes in place today have focused much on selecting the best individuals to breed to maximise genetic diversity, and these recent genetic studies highlight the importance of considering this for the continued success of the species.
Arabian Oryx making their way across the Al Maha Wildlife Reserve, 50 miles outside of Dubai (image from https://www.remotelands.com/travelogues/)
Fauna and Flora International continue to do excellent work for the Arabian Oryx, and you can check them out here: Arabian oryx – Fauna & Flora International (fauna-flora.org)
Phoenix Zoo in Arizona was the home of the original world herd, and you can learn more about their amazing conservation work and history with the Arabian Oryx here: Saving Species: Arabian Oryx – Phoenix Zoo
Awesome videos!
References
Fauna and Flora International
Hetem, R.S. Strauss, W.M. Fick, L.G. Maloney, S.K. Meyer, L.C.R. Shobrak, M. Fuller, A. and Mitchell, D. (2010) ‘Variation in the daily rhythm of body temperature of free living Arabian Oryx: does water limitation drive heterothermy?’ Journal of Comparative Physiology
Marshall, T.C. Sunnucks, P. Spalton, A. Greth, J.M. and Pemberton, J.M. (2006) ‘Use of genetic data for conservation management: the case of the Arabian oryx.’ Animal Conservation
Marshall, T.C. and Spalton, J.A. (2000) ‘Simultaneous inbreeding and outbreeding depression in reintroduced Arabian oryx.’ Animal Conservation
Ostrowski, S. Williams, J.B. Ismael, K. (2003) ‘Heterothermy and the water economy of free-living Arabian Oryx.’ Journal of Experimental Biology
Ostrowski, S. Williams, J.B. Mesochina, P. and Sauerwein, H. (2005) ‘Physiological acclimation of a desert antelope to long term food and water restriction.’ Journal of Comparative Physiology
Phoenix Zoo Species Survival Plan (2011)
Rawahi, Q.A. Mijangos, J.L. Khatkar, M.S. Al Abri, M.A. Al Jahdhami, M.H. Kaden, J. Senn, H. Brittain, K. and Gongora, J. (2022) ‘Rescued back from extinction in the wild: past, present and future of the genetics of the Arabian Oryx in Oman.’ Royal Society Open Science
Spalton, J.A. Lawrence, M.W. and Brend, S.A. (1999) ‘Arabian oryx reintroduction in Oman: successes and setbacks.’ Oryx
Williams, J.B. Ostrowski, S. Bedin, E. and Khairi, I. (2001) ‘Seasonal variation in energy expenditure, water flux and food consumption of Arabian Oryx.’ Journal of Experimental Biology
MASSIVE THANK YOU TO RACHAEL DA SILVA FROM THE UK FOR THIS WRITE UP! PLEASE FOLLOW HER ON INSTAGRAM AND HER WILDLIFE ARTWORK AT TILLY_MINT08
