A species returning from the edge of oblivion captures both scientific rigor and public imagination. This phenomenon occurs in two distinct ways: a species presumed lost is unexpectedly found to have survived undetected, or human intervention actively recovers a population that was functionally extinct. These events redefine the nature of extinction and offer hope for global biodiversity. Understanding how species are declared “no longer extinct” involves examining cases of extreme elusiveness and the results of complex, long-term scientific management programs.
Species Rediscovered After Declared Extinct
The rediscovery of a species long assumed extinct is referred to as a Lazarus taxon. These animals were never truly gone, but they managed to evade scientific documentation, often for decades or centuries, due to remote habitats or secretive behavior. This phenomenon demonstrates the limits of human observation in vast and complex ecosystems.
One celebrated example is the Coelacanth, a lobe-finned fish known only from the fossil record, with the last fossil dating back 66 million years. Its existence was a shock when the first living specimen was caught off the coast of South Africa in 1938. The Coelacanth survived by inhabiting deep-sea environments, typically found in caves and canyons between 500 and 800 feet below the surface, a depth rarely explored until modern times.
The Bermuda Petrel, also known as the Cahow, represents a similar story of evasion. This small, nocturnal seabird was believed extinct for nearly 300 years following the arrival of European settlers and the invasive predators they introduced. In 1951, a small population of seventeen nesting pairs was found on isolated rock islets off the coast of Bermuda. The Cahow’s rediscovery highlighted its reliance on the few remaining predator-free nesting sites.
The Chacoan Peccary, a pig-like ungulate, was known only through sub-fossil remains suggesting it went extinct approximately 12,000 years ago. After a specimen was discovered in 1975 in the remote Gran Chaco region of Paraguay, it was confirmed that a small population had survived in the harsh, dry scrubland. This rediscovery was largely attributed to local knowledge, which maintained awareness of the animal’s existence despite its absence from scientific records. These species showcase how remote geography, specialized behavior, and luck can allow a population to persist beyond the gaze of modern science.
Active Recovery Through Conservation Efforts
A separate category of animals returning from the brink are those rescued through intensive human management. These species were often reduced to a few individuals, necessitating the strategy of removing them from the wild for a controlled recovery. This method focuses on maximizing reproduction and genetic health before reintroducing stable populations into protected habitats.
The California Condor
The California Condor program is a prime example of this intervention, beginning when all 27 remaining wild individuals were taken into captivity by 1987. The program employed “double-clutching,” where the first egg is removed for hand-rearing, prompting the pair to lay a second egg. This method significantly increased the reproductive output of the founding population, which was managed using genetic pedigree information to minimize inbreeding. Today, the total condor population, including both captive and free-flying birds, has grown to over 500 individuals, a result of decades of meticulous breeding and reintroduction efforts.
The Black-footed Ferret
The Black-footed Ferret, a small North American carnivore, was declared extinct in 1979 and rediscovered in Wyoming in 1981. After a disease outbreak, the last 18 ferrets were brought into a captive breeding facility by 1987 to save the species. The ferrets are obligate predators of prairie dogs and rely on their burrows for shelter, meaning recovery efforts required the simultaneous management of prairie dog colonies. Since 1991, thousands of captive-bred ferrets have been reintroduced across 30 sites, establishing a self-sustaining wild population that now includes hundreds of individuals.
The success of these programs relies on continuous human involvement and the application of genetic tools, such as mean kinship analysis, to ensure the maximum genetic diversity from the original founders is retained. The methods are costly and labor-intensive, but they demonstrate that human effort can reverse population declines that have reached a near-extinction status. These recoveries highlight the potential for conservation biology to function as a restorative force in the natural world.
The Theoretical Science of De-Extinction
The most future-focused path to bringing back a species is de-extinction, which involves advanced genetic technology. This process bypasses natural recovery and focuses on either cloning a recently extinct animal or genetically engineering a hybrid that resembles an ancient one. The Pyrenean Ibex, or bucardo, was the first animal to be briefly “de-extincted” using cloning techniques.
Cloning the Pyrenean Ibex
The last bucardo died in 2000, but scientists had preserved tissue samples containing viable DNA. Using somatic cell nuclear transfer, the same technique that created Dolly the sheep, a clone was successfully born in 2003. However, the cloned ibex survived for only minutes due to severe respiratory failure, demonstrating the technical hurdles and high failure rates associated with cloning. This effort also highlighted the limitation that no available genetic material from a male existed, making the establishment of a breeding population impossible.
Genetic Engineering and the Mammoth
Current de-extinction efforts are focused on genetic engineering, exemplified by projects aiming to create a proxy for the Woolly Mammoth. Scientists are using the CRISPR gene-editing tool to insert cold-resistant traits, such as dense fur, a thick fat layer, and small ears, from the mammoth genome into the cells of its closest living relative, the Asian elephant. Since ancient DNA is too degraded for full cloning, the goal is to create a genetically modified, cold-weather elephant hybrid that could potentially re-inhabit the Arctic tundra ecosystem.
These projects raise questions regarding the allocation of resources and the ecological role of a genetically engineered organism. Many scientists debate whether the substantial financial and technical investment should instead be directed toward protecting currently endangered species. Furthermore, the resulting animal would not be a perfect copy of the original mammoth, but a hybrid, introducing a novel creature into an ecosystem that has changed significantly since the mammoth’s disappearance.