Reborn to Be Wild

In 2000, the International Union for Conservation of Nature made it official: The scimitar-horned oryx, an antelope that once abundantly roamed the grasslands fringing Africa’s Sahara Desert, was functionally extinct in the wild. 

But just over 20 years later, the union decisively reversed its assessment, downlisting the species to “endangered” status, thanks to a global coalition of governments, conservation organizations and scientists who reintroduced these animals from captivity back into natural habitats.

Now, University of Maryland researchers have partnered with the Smithsonian’s National Zoo and Conservation Biology Institute (NZCBI) to assess how the reintroduced oryx population is weathering its comeback. 

“It’s one of conservation’s best success stories, so it’s important to find out the long-term consequences of their return,” said biological sciences Ph.D. student Gayatri Anand, who works with Distinguished University Professor of Biology Bill Fagan to study movement ecology. “Have these scimitar-horned oryx changed, in terms of their social behavior or migratory knowledge, from their original wild versions? And if so, how?” 

Since 2016, nearly 350 scimitar-horned oryx from a captive breeding herd managed by the Environment Agency-Abu Dhabi have been released into the Réserve de Faune de Ouadi Rimé-Ouadi Achim in central Chad, a protected area roughly the size of Maine. The wild population now numbers around 650-900, with the majority of animals born in Chad. By most typical benchmarks for similar programs, the oryx reintroduction is working.

“This is one of the very, very rare cases for a large mammal to be brought back from extinction in the wild,” said Postdoctoral Researcher Marron McConnell Ph.D. ’26, who also collaborates with Fagan. “Reintroducing these animals from captivity is extremely complex and difficult. Only a few other comparable examples come to mind, such as the Arabian oryx and Przewalski’s horse.” 

But bringing a species back from extinction is only the beginning. Can an animal that has spent generations in captivity actually learn to be wild again? Around 2022, research ecologists Jared Stabach and Katherine Mertes of NZCBI initiated a collaboration with Fagan and his research group to help answer that question.

Because the species was extinct in the wild for so long, almost everything known about its social behavior came from captive populations—which are typically smaller, sex-biased and managed in fenced enclosures. When the first 21 oryx were released into the reserve in 2016, they entered a landscape with no social world. McConnell was excited to see how the reintroduced animals reformed the social bonds that build an organized population.

“They had to construct a society from scratch,” explained McConnell, whose research focus is on animal social dynamics. “I study how the new oryxes did that, how it grew over time, and how the structure and demographics of these social modules developed.”

To trace that development, McConnell drew on a mix of daily observations by a full-time field monitoring team, genetic analyses documenting kinship among the oryx released into Chad and GPS collar data. Her analysis found that reintroduced oryx were a particularly “gregarious species.” 

“The oryx love communicating with each other, but they don’t form fixed herds,” McConnell said. “Instead, they move through what ecologists call ‘fission-fusion’ dynamics—constantly mixing, splitting apart and reforming into new groupings.” 

Anand’s research takes on a different mystery: migration. Historically, this species of oryx is believed to have followed seasonal “green waves”—pulses of vegetation growth that move north through the grasslands along the Sahara Desert, as the rainy season progresses. 

But in ungulates (hoofed mammals like the oryx, along with deer, bison and horses), migration isn't instinct. It’s culture. 

“Knowledge of migratory routes isn't inborn in ungulates. Instead, it’s passed from parent to child, so when a population goes locally extinct, that knowledge disappears with it,” Anand explained. “There are studies of bighorn sheep, bison and red deer that have this same pattern. Without experienced animals to follow, reintroduced populations don’t know where to go.”

Anand found early evidence that oryx may have adapted to their lack of knowledge. 

“It looks like there is a learning process going on between these newer generations of oryxes, now that the earliest batch has gained more experience tracking resource waves,” Anand said. “The population is forming complicated social and movement structures to ensure that they get to where they need to go.”

The wealth of GPS data from reintroduced oryx represents more than just the success of one conservation effort. For Fagan’s group and many other movement ecologists worldwide, this project is just the beginning.

“The oryx dataset has years and years of crucial information about these animals just waiting to be found,” McConnell said. “From what we’ve worked with in the movement data, we’re able to access insights into things like their social structures, adaptive behaviors and even potential emergency warning signs for future disease events.” 

Lessons learned here are applicable to similar animals living in seasonally variable landscapes, Anand added. “This work can also serve as a roadmap for future reintroductions of other species elsewhere, potentially bringing back other functionally extinct animals from extinction.”