For almost 100 years, researchers have been baffled as to how tiny, flightless birds made their way to an isolated island.

The researchers of a new study now know how the birds got to the island and successfully colonized it.

The World’s Smallest Flightless Bird

Inaccessible Island rails are the world’s smallest flightless birds, weighing in at just about 34 to 49 grams. But apart from the birds’ size and striking features, what’s even more incredible about the tiny birds is that they live on an island aptly named Inaccessible Island, an isolated island in the middle of the southern Atlantic Ocean.

It was in 1923 when British physician Percy Lowe of the British Museum first described the Inaccessible Island rail and gave it a separate Atlantisia genus, after the mythical island of Atlantis. Back then, he believed that the birds got to the island by walking to it via a foot bridge that had previously linked the island to Africa or South America.

However, the real story of how the Inaccessible Island rails got to the island remained a mystery for nearly a hundred years.

From South America

Now, researchers of a new study published in Molecular Phylogenetics and Evolution may have cracked the mystery. Researchers analyzed the DNA samples they collected from a male Inaccessible Island rail seven years ago and compared it to the DNA of its other relatives in other places such as Africa and South America.

What they found was that its DNA was closest to its relatives in South America, the dot-winged crake, suggesting that is where they originally came from. By looking further into the differences between the DNA of the two species, the researchers also found that it would have taken 1.5 million years for the two birds to accumulate genetic changes, which could mean that the Inaccessible Island rails traveled to the island around that time.

Bird Colonizers

According to researchers, it’s possible that the birds got to the island either by flying or from floating debris, then the birds evolved to lose their ability to fly over the course of time since the island was abundant in food and free of predators.

Evidently, this is not uncommon for birds in the rail species. In fact, at least 32 isolated, living rail species are less capable of flying, or have lost the ability to fly entirely.

Today, while Inaccessible Island rails continue to thrive, efforts to prevent the accidental introduction of predators such as rats or cats are very important in keeping the species alive.