Once we reduce a species to a single individual, no amount of human desperation can bring them back from the brink.
Illustration by Kayla Oliver
The Christmas Island forest skink was once abundant and widespread on Christmas Island. In the late 1990s, one researcher saw up to 80 skinks basking and foraging around a single fallen tree. Then, for reasons that still aren’t clear, the species collapsed.
Within a decade, the forest skink (Emoia nativitatis) was restricted to a single site in the island’s southwest, and researchers swooped in to capture and preserve as many individuals as possible. Their response came too late – only three forest skinks were ever brought into captivity, all female. By 2012, only a single individual remained. Affectionately named Gump, she lived out her final years alone in a small enclosure, and died on May 31, 2014 to very little media fanfare.
“It was sad, but it wasn’t unexpected because we did have her in captivity for a couple of years,” said Dion Maple, Christmas Island National Park’s natural resource manager, in an interview last year. “While we don’t know for sure how long these animals can live for, everything dies eventually, and even though it represented the last of a species, we hadn’t found any others.”
Gump was an endling, the last member of her species. The decline of any population is painful to witness, but that last cut is definitely the deepest. Once we reduce a species to a single individual, it’s already too late – no amount of human desperation can reverse the damage we’ve done. All we’re left with is an eerie moment on the cusp of extinction, to ponder how it all went wrong.
“Benjamin” the thylacine (left) and Lonesome George the Pinta Island tortoise (right) are well-known endlings. Wikimedia Commons (public domain); Arturo de Frias Marques/Wikimedia Commons (CC BY-SA 3.0)
The managers on Christmas Island have felt this hollow feeling far too often. In August 2009, scientists on an eleventh-hour rescue mission recorded the chirpy feeding call of the last Christmas Island pipistrelle (Pipistrellus murrayi). For three nights, this tiny male bat chased insects through the canopy, deftly dodging the scientists’ mist nets and tunnel traps, before falling silent on the fourth night. The scientists had hoped to capture the pipistrelle for captive breeding, but instead only managed to record his death-knell.
Dion Maple would love for the pipistrelle to still be around, hiding in the more rugged corners of Christmas Island, but he isn’t hopeful. “We were monitoring them for years before they went extinct, and for years after that we continued to do so,” he said. “So I’m pretty confident that they won’t show up again.”
The Christmas Island endlings are the latest in a long, sad human tradition. The most famous endling was Lonesome George, the last Pinta Island tortoise, who died in captivity in June 2012 after decades of unsuccessful mating attempts. Likewise, the taxidermied remains of Martha the passenger pigeon have been called “an organic monument… the embodiment of extinction itself.” Back home in Australia, brief snippets of film from Hobart Zoo give us our only good look at the thylacine, whose endling – said to have been named “Benjamin” – died in 1936.
This can all make for some very sombre bedtime reading. The media is generally so quiet on the subject of extinctions that you’d be forgiven for thinking they were a thing of the past – a relic of a less enlightened bygone era. But no, extinction is alive and well. The Hawaiian snail Achatinella apexfulva is now confined to a small container at the University of Hawaii. Likewise, a Panamanian treefrog named Toughie has been the last of his species for nearly four years and counting.
Toughie, the last known Rabb's fringe-limbed treefrog (Ecnomiohyla rabborum), lives alone at the Atlanta Botanical Garden. Brian Gratwicke/Flickr (CC BY 2.0)
So what can we do about this extinction epidemic? Once a species has dwindled to only a few individuals, there’s arguably little that we can do – or, at least, any conservation program would be extremely costly with a low chance of success. Some of our more ambitious scientists suggest cloning species back from extinction. At first blush this sounds more like science-fiction, but actually it has already been done.
The Pyrenean ibex (Capra pyrenaica pyrenaica), or bucardo, was a subspecies of Spanish wild goat that lived high in the Pyrénées at the border of Spain and France. With their large, majestically curved horns, the ibex would’ve been quite a sight traversing the rocky mountain slopes. But centuries of hunting and livestock competition gradually wore down the population, until only three individuals were known to persist in 1989. The endling was a female named Celia, who in January 2000 was found dead with her skull crushed beneath a fallen tree. End of subspecies, end of story.
But not quite. Nine months earlier, Spanish scientists had taken a tissue sample from Celia, which now sat in cryopreservation. Celia was then cloned using a process similar to that which created Dolly the sheep: eggs were taken from domestic goats, their nuclei removed and replaced with Celia’s nuclei. These reconstructed embryos were then placed back into surrogate mothers that would carry them until birth.
It was a terribly inefficient procedure, but the scientists’ persistence eventually paid off. From 439 reconstructed embryos, one survived full term. The Pyrenean ibex became “unextinct” on July 30, 2003, when a 2.6kg ibex kid was gently pulled from the womb of her surrogate mother. This newborn was anatomically normal but for some major lung defects, including an extra lobe that filled much of her thoracic cavity and made breathing difficult. She died several minutes after birth.
The Pyrenean ibex (Capra pyrenaica pyrenaica), illustrated here in 1898, remains extinct despite multiple cloning attempts. Joseph Wolf/Wikimedia Commons (public domain)
The fleeting revival of the Pyrenean ibex gives hope to future cloning attempts, especially given technological advances in the last decade. But is cloning really a viable option for conserving critically endangered species? Even if we did produce a few healthy cloned individuals, we’d still be left with a tiny, genetically homogenous population, unlikely to survive in the wild in the long term. For instance, the extinct passenger pigeon has been touted as a prime candidate for cloning, yet in life it was an incredibly social species, forming huge flocks with millions of individuals. A tiny captive population of cloned birds would surely struggle to re-establish themselves in the absence of any existing social structure.
There is also the question of habitat. Many endangered species got that way because of habitat destruction or degradation, and what remains today may be unsuitable to support the species. In the US, the Wyoming toad (Anaxyrus baxteri) went extinct in the wild in 1991, but has since been reintroduced into a few small alpine lakes at Mortenson Lake National Wildlife Refuge. Despite a detailed recovery plan, the species’ future looks uncertain. Wild toads are being ravaged by chytridiomycosis, an infectious fungal disease that is destroying amphibian populations worldwide. Without effective control measures for chytrid fungus, the Wyoming toad is one species that simply can’t persist without our continued life-support.
It could be that we’re wasting our time and money preserving species so close to extinction. Some scientists advocate a form of conservation triage, that we should focus our efforts on a subset of threatened species. This is a logical approach to allocating our limited conservation dollars, but it can be very unsatisfying: it means writing off entire species as unsavable, and then watching as they go extinct.
“We call those living dead or zombie species, because the likelihood of them persisting for any reasonable amount of time in the future is pretty low,” said Corey Bradshaw, director of the Climate and Ecology Centre at the University of Adelaide, in 2014.
So how, then, do we decide which species are worth saving? Proponents of conservation triage say that our resources are best spent on ecologically important species that would benefit most from our intervention, especially if it can be done cheaply. Using this reasoning, it’s probably time to abandon the orange-bellied parrot and helmeted honeyeater, two critically endangered birds subject to expensive, marginally successful captive breeding programs. But both birds have something important going for them: they’re charismatic, and they’ve captured the public interest. Indeed, the helmeted honeyeater was adopted as Victoria’s state faunal emblem in 1971.
Species on the edge of extinction may be a long shot, but sometimes they’re a long shot worth taking. The Lord Howe Island stick insect is one of the decade's biggest success stories. Thought extinct for 80 years, the species was rediscovered in 2001 on Balls Pyramid, clinging to a patch of debris beneath a single Melaleuca shrub. From two captured breeding pairs, Zoos Victoria now has an insurance population in the thousands, with plans to reintroduce the insect to Lord Howe Island.
Also consider the story of Phil Pister, a fishery biologist for the California Department of Fish and Game. On a warm evening in August 1969, Pister found himself alone at Fish Slough, a desert marshland that was home to the last surviving population of Owens pupfish (Cyprinodon radiosus). As he watched in horror, hundreds of pupfish rose belly-up to the surface, suffocating in a stagnant, rapidly-drying pond.
Realising that time was short, Pister netted the surviving fish into two buckets and shakily carried them upstream to more suitable waters.
The entire population of Owens pupfish (Cyprinodon radiosus) was carried in two buckets. Joe Ferreira, California Department of Fish and Wildlife/Flickr (CC BY 2.0)
“Such are the reflections of a biologist,” he later wrote, “who, for a few frightening moments long ago, held an entire species in two buckets, one in either hand, with only himself standing between life and extinction.”
Today, there are four carefully managed populations of Owens pupfish in California. The species isn’t out of the woods yet, but it’s looking much healthier. The quick-thinking efforts of a single man retrieved a species from the brink. We must never forget that this is within our power.
Edited by Ellie Michaelides, and sponsored by Emma Colvill
