The Aldabra rail (Dryolimnas cuvieri) is a somewhat impressive bird that can be found in Madagascar, in the Seychelles archipelago. Researchers have discovered that this species vanished from the Aldabra Islands 136,000 years ago... and mysteriously reappeared last year! How can that be?
An interesting bird
The Aldabra rail doesn't migrate for a very good reason: it can't fly. Which isn't shocking, as many birds, like penguins and ostriches, are flightless. But what makes the Aldabra rail exceptional in the eyes of scientists is that 136,000 years ago, the Aldabra Islands were completely covered by the ocean, wiping out the entire species, which, because it was unable to fly, did not manage to escape.
10,000 years ago, as the sea level dropped, the atoll came out from the depths of the Indian Ocean. Years later, you can now, once again, spot this bird all over the island. But how did it rise from the dead?
Scientists just can't wrap their heads around it. So, they've decided to examine fossils of this bird from before and after the flood. Doctor Julian Hume, a palaeontologist at the Natural History Museum in London, explained:
These fossils are irrefutable evidence that a member of Rallidae colonized the atoll, most likely from Madagascar, and became flightless independently on each occasion
Scientists call this iterative (or repeated) evolution, a very rare occurrence made possible by 'the absence of terrestrial predators or competing mammals.' explains Professor David Martill, of the University of Portsmouth. This is also the first time that we're seeing irrefutable proof of this type of evolution in birds.