The Aldabra Atoll was once home to a number of different animals about 136,000 years ago. But during that period, the idyllic island became engulfed by water from the Indian Ocean, killing the creatures that resided there. Incredibly, though, one of those unfortunate life forms wouldn’t stay extinct forever.
Located outside the Seychelles, the Aldabra Atoll is a picturesque spot that now houses hundreds of unique animals. One of the most notable creatures in that list is the giant tortoise. According to the National History Museum’s website, over 100,000 of them call the area home. Yet as we’ve already mentioned, the island wasn’t always habitable.
Indeed, the animals that lived on the Aldabra Atoll around 136,000 years ago were wiped out as a result of major changes in the temperature. Yes, the altering weather caused rising sea levels to spill across the island, before it eventually vanished from view. But as time went on, another significant event occurred.
Thousands of years after the Aldabra Atoll was submerged, it appeared again in the Indian Ocean thanks to an ice age. You see, the sharp drops in temperature saw sea levels return to their previous state. And amazingly, while local animals have now reclaimed the island, one of the previous inhabitants came back from extinction.
At this point, you’re probably curious as to the identity of this somewhat miraculous animal. Well, it’s referred to as the Aldabra rail bird, a species that’s around the same height as a chicken. The creature sports dark feathers on its back and a lighter brown shade across its face. Yet that’s not all.
In addition to those colors, the Aldabra rail bird has a white streak running down its neck. That might not seem too important, but this feature gives us some insight into the animal’s past. As it turns out, it comes from a lineage of birds named the white-throated rail.
Now, the white-throated rail could fly at first, but it evolved to become flightless. And of course, its subspecies, the Aldabra rail bird, can’t fly either. It’s believed that once the former settled on the island, its biological makeup changed over time. For you see, the Aldabra Atoll didn’t house any predatory animals that would attack them. So they had no need to glide away.
However, that biological change eventually came at a cost 136,000 years ago. As we highlighted earlier, the Indian Ocean started to spill over into the Aldabra Atoll at that time. That wouldn’t have been a major issue for any of the flying birds, as they could just migrate to another area.
Unfortunately, the Aldabra rail bird didn’t have that luxury, so the animals were stuck on the island when the water came in. Due to that, they all perished once the Aldabra Atoll was submerged, drowning with the other life forms. The event appeared to mark their extinction, before the creatures made a stunning comeback.
On that note, you might be surprised to hear that the Aldabra rail bird isn’t the only animal to come back from the dead. In fact, there are many different species that have followed a similar path down the years. One such life form emerged in February 2019, leaving experts stunned.
Yes, the animal in question was the Fernandina giant tortoise. These specimens apparently died out after 1906, as that year marked the last time anyone saw one on Fernandina Island, in the Galȧpagos. But that soon changed in the early part of 2019, when the Giant Tortoise Restoration Initiative stumbled across one of the creatures.
Upon closer inspection, it was confirmed that the Fernandina giant tortoise was female and more than a century old. If that wasn’t enough, there were said to be additional markings on the island too, suggesting that she might not be the last of her kind. In the end, the animal was transported to the Fausto Llerena Breeding Center to ensure her protection.
Meanwhile, another animal emerged following a long absence back in 1951. Prior to that, experts believed that the Bermuda cahow, a kind of petrel bird, had been gone for well over 300 years, dying out in the wild. Yet amazingly, 36 of them were found near Nonsuch Island, Bermuda.
So conservationists tried to increase them in number over the next few decades, with encouraging results. You see, by 2018 there were more than 130 breeding pairs in the wild. And alongside that, 71 Bermuda cahows found their wings that year as well. But the hard work doesn’t appear to be done just yet.
Jeremy Madeiros, who plied his trade as a conservation officer, spoke to the National Geographic website about the importance of this story. “It’s an ongoing recovery,” he said in March 2019. “[And it’s] an example for threatened species around the world in an era when encroachment on and destruction of habitats is putting more species at risk than ever before.”
A few years before the Bermuda cahow was rediscovered, a different creature hit the headlines. When the dinosaurs were wiped out millions of years ago, the coelacanth fish was believed to be among the casualties. And no one had any reason to believe that they weren’t extinct, but that mindset quickly changed in 1938.
During that period, a woman named Marjorie Courtenay-Latimer was walking through a fish market in South Africa. While looking at the catches, she caught sight of a large, live coelacanth, which she subsequently saved. Unsurprisingly, after a 66 million year absence, that discovery generated plenty of attention.
Since then, it’s been confirmed that just two types of coelacanth can be found in the wild right now. And in addition to that, swimmers have noted sightings of the fish in various locations around East Africa. Indeed, they’ve been seen in waters near Kenya, Mozambique, Tanzania and Madagascar.
While those somewhat ancient animals were close to being completely wiped from the earth, there are more modern species that almost suffered the same fate. The giant panda is one of these, as their numbers plummeted throughout the 1980s. As a result, there were said to be just hundreds left alive.
So conservationists tried to protect the remaining pandas, with plenty of money being spent to aid their efforts. And due to that work, the species was saved from extinction. Yes, by 2018 there were over 1,800 pandas out in the open, while some 300 more were staying safe in zoos, according to National Geographic.
Furthermore, animals like the Louisiana black bear and the lesser long-nosed bat were in comparable positions in the past too. For instance, the latter species suffered countless losses over three decades ago, leaving just under a thousand of them alive. As for the bears, their numbers dwindled dangerously in the early 1990s.
Following those scares, the two animals have managed to avoid extinction. When it comes to the Louisiana black bear, it’s believed there were up to 750 of them roaming around in 2018. Meanwhile, the lesser long-nosed bat regained a healthy population during that time as well. Indeed, the U.S. Fish and Wildlife Service claimed that their numbers stood at over 200,000.
Incredibly, though, one other creature found themselves in an even more perilous position. The animal in question was the Vancouver Island marmot, living in British Columbia, Canada. After loggers worked their way through the surrounding region the decade before, around 20 of the marmots were left alive back in 2003.
In the end, the Vancouver Island marmots were eventually pulled back from the brink thanks to some hard work. Yes, once the Marmot Recovery Foundation was set up, their population received a much needed boost. Indeed, it’s believed that you could find up to 200 of them in the wild 15 years on from their brush with death.
On that note, let’s redirect our focus to the Aldabra rail bird. In our lifetime, the species has existed on the Aldabra Atoll. But in May 2019, two academics revealed a shocking piece of information about the bird’s strange evolutionary past. And they published it in the Zoological Journal of the Linnean Society.
Now, the authors had looked at two separate bird fossils. The first dated back to the flooding 136,000 years ago and belonged to the Aldabra rail bird. As for the second, it was a younger fossil, dating back to around 100,000 years ago. Interestingly, that latter time frame lined up with when the island re-emerged from the water.
After studying the bones, the researchers realized that the younger set showed some interesting signs. For you see, those remains belonged to a white-throated rail, the species that spawned the Aldabra rail bird. And upon closer inspection, they noted it was beginning to follow the same evolutionary path as the latter.
If you’re wondering how that’s possible, let’s cast our minds back to the Aldabra rail bird’s past. As we already know, the species started out as a white-throated rail that lived in Madagascar. When their numbers ballooned up, several of them started to fly away, looking for another home in the region.
Plenty of white-throated rails died in the end, yet the ones who arrived on the Aldabra Atoll escaped the same fate. From there, they went through the biological changes that we spoke about earlier. So that brings us back to the authors’ findings, which suggest that the process started happening again when the island returned to normal.
Incredibly, the Aldabra rail bird essentially evolved itself back into existence, leaving the researchers stunned. To explain more, one of them released a statement after the paper was published in May 2019. His name was David Martill, and he plied his trade at the University of Portsmouth as a paleobiologist.
Martill said, “We know of no other example in rails, or of birds in general, that demonstrates this phenomenon so evidently. Only on Aldabra, which has the oldest palaeontological record of any oceanic island within the Indian Ocean region, is fossil evidence available that demonstrates the effects of changing sea levels on extinction and recolonization events.”
“Conditions were such on Aldabra, the most important being the absence of terrestrial predators and competing mammals, that a rail was able to evolve flightlessness independently on each occasion,” Martill added to his statement. It’s a truly remarkable process, but could a similar thing happen for any other extinct animals today?
Let’s take the dodo for example. Prior to their extinction in the 1600s, these unique-looking birds resided on the island of Mauritius. And much like the Aldabra rail birds, they evolved into flightless animals. Yet despite the similarities, dodos won’t follow in the footsteps of the aforementioned creatures. Why?
Well, the Aldabra rail bird’s re-emergence is usually referred to as “iterative evolution.” The term is used to describe the process when an animal experiences the same evolutionary changes as others in its family tree. And to do so, they have to be almost identical to their relatives in the first place – lacking only a feature or two. In the case of the dodo, there aren’t any creatures from its lineage that could realistically mirror that.
Indeed, the dodo was part of a family tree that spawned doves and pigeons, which are much smaller in size. Today, a bird named the Nicobar pigeon is believed to be its closest-living relative, roaming around parts of India. But again, given its stature and living conditions, that bird is unlikely to go through iterative evolution.
Meanwhile, the second author of the Zoological Journal of the Linnean Society paper provided more insight. His name was Julian Hume, and he held a position at the National History Museum in London, England. As we’ll soon see, Hume summed up what they found.
Yes, Hume said, “These unique fossils provide irrefutable evidence that a member of the rail family colonized the atoll, most likely from Madagascar, and became flightless independently on each occasion. [The] fossil evidence presented here is unique for rails. And [it] epitomizes the ability of these birds to successfully colonize isolated islands and evolve flightlessness on multiple occasions.”
However, while the findings are definitely exciting, Hume brought up a worrying point a bit later. During an interview on the National History Museum’s website, he spoke about the dangers of climate change now. In his mind, the flooding incident 136,000 years ago might well happen again to certain islands.
“Our research has shown that low islands and atolls and associated fauna have always been vulnerable to climate change, and that complete turnovers of fauna can occur,” Hume explained in April 2019. “This natural process has been going on for millennia, but it is extremely rare to see it in the fossil record.”
Hume then concluded, “Unfortunately, due to human activity, climate change is now happening at an unprecedented rate. And many low islands around the world may be subject to similar inundation events that occurred on Aldabra over 118,000 years ago.” But if that transpires, the evidence suggests that the Aldabra rail birds of today could eventually re-emerge.